Make ConfigLib Java 8 compatible

.travis.yml

@@ -1,3 +1,5 @@
 language: java
 jdk:
-    oraclejdk10
+  - oraclejdk8
+  - oraclejdk9
+  - oraclejdk10

ConfigLib-Bukkit/src/main/resources/plugin.yml

@@ -1,5 +1,5 @@
 name: ConfigLib
 author: Exlll
 
-version: 2.0.0
+version: 2.0.1
 main: de.exlll.configlib.ConfigLib

ConfigLib-Bungee/src/main/resources/plugin.yml

@@ -1,5 +1,5 @@
 name: ConfigLib
 author: Exlll
 
-version: 2.0.0
+version: 2.0.1
 main: de.exlll.configlib.ConfigLib

ConfigLib-Core/src/main/java/de/exlll/configlib/Comments.java

@@ -41,7 +41,7 @@ public final class Comments {
     private static List<String> getComments(AnnotatedElement element) {
         Comment comment = element.getAnnotation(Comment.class);
         return (comment != null)
-                ? List.of(comment.value())
+                ? Arrays.asList(comment.value())
                 : Collections.emptyList();
     }
 

ConfigLib-Core/src/main/java/de/exlll/configlib/Reflect.java

@@ -7,14 +7,11 @@ import de.exlll.configlib.annotation.NoConvert;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
-import java.util.Arrays;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 
 enum Reflect {
     ;
-    private static final Set<Class<?>> SIMPLE_TYPES = Set.of(
+    private static final Set<Class<?>> SIMPLE_TYPES = new HashSet<>(Arrays.asList(
             Boolean.class,
             Byte.class,
             Character.class,
@@ -24,8 +21,8 @@ enum Reflect {
             Float.class,
             Double.class,
             String.class
-    );
-    
+    ));
+
     static boolean isSimpleType(Class<?> cls) {
         return cls.isPrimitive() || SIMPLE_TYPES.contains(cls);
     }

ConfigLib-Core/src/main/java/de/exlll/configlib/configs/yaml/YamlComments.java

@@ -31,7 +31,7 @@ final class YamlComments {
             Map.Entry<String, List<String>> entry
     ) {
         String fieldComments = commentListToString(entry.getValue());
-        return Map.entry(entry.getKey(), fieldComments);
+        return new MapEntry<>(entry.getKey(), fieldComments);
     }
 
     private String commentListToString(List<String> comments) {
@@ -43,4 +43,32 @@ final class YamlComments {
     private String toCommentLine(String comment) {
         return comment.isEmpty() ? "" : "# " + comment;
     }
+
+    private static final class MapEntry<K, V> implements Map.Entry<K, V> {
+        private final K key;
+        private V value;
+
+        public MapEntry(K key, V value) {
+            this.key = key;
+            this.value = value;
+        }
+
+        @Override
+        public K getKey() {
+            return key;
+        }
+
+        @Override
+        public V getValue() {
+            return value;
+        }
+
+        @Override
+        public V setValue(V value) {
+            V old = this.value;
+            this.value = value;
+            return old;
+        }
+    }
+
 }

ConfigLib-Core/src/main/java/de/exlll/configlib/configs/yaml/YamlSource.java

@@ -8,6 +8,7 @@ import org.yaml.snakeyaml.Yaml;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -103,7 +104,7 @@ final class YamlSource implements ConfigurationSource<YamlConfiguration> {
 
         private void addFieldComments() {
             if (comments.hasFieldComments()) {
-                List<String> dumpLines = List.of(dump.split("\n"));
+                List<String> dumpLines = Arrays.asList(dump.split("\n"));
                 addDumpLines(dumpLines);
             } else {
                 builder.append(dump);

ConfigLib-Core/src/test/java/de/exlll/configlib/CommentsTest.java

@@ -3,9 +3,8 @@ package de.exlll.configlib;
 import de.exlll.configlib.annotation.Comment;
 import org.junit.jupiter.api.Test;
 
-import java.util.List;
-import java.util.Map;
-
+import static de.exlll.configlib.util.CollectionFactory.listOf;
+import static de.exlll.configlib.util.CollectionFactory.mapOf;
 import static org.hamcrest.Matchers.empty;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
@@ -27,11 +26,11 @@ public class CommentsTest {
         assertThat(comments.getFieldComments().entrySet(), empty());
 
         comments = Comments.ofClass(B.class);
-        assertThat(comments.getClassComments(), is(List.of("B")));
+        assertThat(comments.getClassComments(), is(listOf("B")));
         assertThat(comments.getFieldComments().entrySet(), empty());
 
         comments = Comments.ofClass(C.class);
-        assertThat(comments.getClassComments(), is(List.of("C", "D")));
+        assertThat(comments.getClassComments(), is(listOf("C", "D")));
         assertThat(comments.getFieldComments().entrySet(), empty());
     }
 
@@ -47,9 +46,9 @@ public class CommentsTest {
 
         Comments comments = Comments.ofClass(A.class);
         assertThat(comments.getClassComments(), empty());
-        assertThat(comments.getFieldComments(), is(Map.of(
-                "b", List.of("b"),
-                "c", List.of("c", "d")
+        assertThat(comments.getFieldComments(), is(mapOf(
+                "b", listOf("b"),
+                "c", listOf("c", "d")
         )));
     }
 }

ConfigLib-Core/src/test/java/de/exlll/configlib/FieldMapperConverterTest.java

@@ -12,6 +12,9 @@ import java.util.Map;
 import java.util.Set;
 
 import static de.exlll.configlib.FieldMapperHelpers.*;
+import static de.exlll.configlib.util.CollectionFactory.listOf;
+import static de.exlll.configlib.util.CollectionFactory.mapOf;
+import static de.exlll.configlib.util.CollectionFactory.setOf;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
 
@@ -39,7 +42,7 @@ public class FieldMapperConverterTest {
             implements Converter<Point2D, List<Integer>> {
         @Override
         public List<Integer> convertTo(Point2D element, ConversionInfo info) {
-            return List.of(element.x, element.y);
+            return listOf(element.x, element.y);
         }
 
         @Override
@@ -57,7 +60,7 @@ public class FieldMapperConverterTest {
         public Map<String, String> convertTo(Point2D element, ConversionInfo info) {
             int x = element.x;
             int y = element.y;
-            return Map.of("p", x + ":" + y);
+            return mapOf("p", x + ":" + y);
         }
 
         @Override
@@ -153,7 +156,7 @@ public class FieldMapperConverterTest {
             @Convert(NullConverter.class)
             String s = "string";
         }
-        Map<String, Object> map = Map.of("s", "value");
+        Map<String, Object> map = mapOf("s", "value");
         A a = instanceFromMap(new A(), map);
         assertThat(a.s, is("string"));
     }
@@ -190,7 +193,7 @@ public class FieldMapperConverterTest {
             @Convert(IntToStringConverter.class)
             int i = 1;
         }
-        A i = instanceFromMap(new A(), Map.of("i", "10"));
+        A i = instanceFromMap(new A(), mapOf("i", "10"));
         assertThat(i.i, is(10));
     }
 
@@ -203,8 +206,8 @@ public class FieldMapperConverterTest {
             Point2D p2 = new Point2D();
         }
         Map<String, Object> map = instanceToMap(new A());
-        assertThat(map.get("p1"), is(List.of(1, 2)));
-        assertThat(map.get("p2"), is(Map.of("p", "1:2")));
+        assertThat(map.get("p1"), is(listOf(1, 2)));
+        assertThat(map.get("p2"), is(mapOf("p", "1:2")));
     }
 
     @Test
@@ -215,9 +218,9 @@ public class FieldMapperConverterTest {
             @Convert(PointToMapConverter.class)
             Point2D p2 = new Point2D();
         }
-        Map<String, Object> map = Map.of(
-                "p1", List.of(10, 11),
-                "p2", Map.of("p", "11:12")
+        Map<String, Object> map = mapOf(
+                "p1", listOf(10, 11),
+                "p2", mapOf("p", "11:12")
         );
         A i = instanceFromMap(new A(), map);
         assertThat(i.p1.x, is(10));
@@ -277,7 +280,7 @@ public class FieldMapperConverterTest {
             @Convert(TestSubClassConverter.class)
             TestSubClass a = new TestSubClass();
         }
-        Map<String, Object> map = Map.of(
+        Map<String, Object> map = mapOf(
                 "a", 1
         );
         String msg = "The value for field 'a' with type 'TestSubClass' " +
@@ -294,7 +297,7 @@ public class FieldMapperConverterTest {
         class D {
             char d;
         }
-        Map<String, Object> map = Map.of(
+        Map<String, Object> map = mapOf(
                 "c", "", "d", "12"
         );
         String msg = "The value for field 'c' with type 'char' " +
@@ -313,7 +316,7 @@ public class FieldMapperConverterTest {
         class B {
             String b = "string";
         }
-        Map<String, Object> map = Map.of(
+        Map<String, Object> map = mapOf(
                 "b", 2
         );
         String msg = "The value for field 'b' with type 'String' " +
@@ -327,7 +330,7 @@ public class FieldMapperConverterTest {
         class A {
             LocalTestEnum e = LocalTestEnum.T;
         }
-        Map<String, Object> map = Map.of(
+        Map<String, Object> map = mapOf(
                 "e", "V"
         );
         String msg = "The value for field 'e' with type 'LocalTestEnum' " +
@@ -340,10 +343,10 @@ public class FieldMapperConverterTest {
     void instanceFromMapCatchesClassCastExceptionOfUnknownEnumConstantsInLists() {
         class A {
             @ElementType(LocalTestEnum.class)
-            List<List<LocalTestEnum>> l = List.of();
+            List<List<LocalTestEnum>> l = listOf();
         }
-        Map<String, Object> map = Map.of(
-                "l", List.of(List.of("Q", "V"))
+        Map<String, Object> map = mapOf(
+                "l", listOf(listOf("Q", "V"))
         );
         ConfigurationException ex = assertIfmThrowsCfgException(new A(), map);
         Throwable cause = ex.getCause();
@@ -357,10 +360,10 @@ public class FieldMapperConverterTest {
     void instanceFromMapCatchesClassCastExceptionOfUnknownEnumConstantsInSets() {
         class A {
             @ElementType(LocalTestEnum.class)
-            Set<List<LocalTestEnum>> s = Set.of();
+            Set<List<LocalTestEnum>> s = setOf();
         }
-        Map<String, Object> map = Map.of(
-                "s", Set.of(List.of("Q", "V"))
+        Map<String, Object> map = mapOf(
+                "s", setOf(listOf("Q", "V"))
         );
         ConfigurationException ex = assertIfmThrowsCfgException(new A(), map);
         Throwable cause = ex.getCause();
@@ -374,10 +377,10 @@ public class FieldMapperConverterTest {
     void instanceFromMapCatchesClassCastExceptionOfUnknownEnumConstantsInMaps() {
         class A {
             @ElementType(LocalTestEnum.class)
-            Map<Integer, List<LocalTestEnum>> m = Map.of();
+            Map<Integer, List<LocalTestEnum>> m = mapOf();
         }
-        Map<String, Object> map = Map.of(
-                "m", Map.of(1, List.of("Q", "V"))
+        Map<String, Object> map = mapOf(
+                "m", mapOf(1, listOf("Q", "V"))
         );
         ConfigurationException ex = assertIfmThrowsCfgException(new A(), map);
         Throwable cause = ex.getCause();

ConfigLib-Core/src/test/java/de/exlll/configlib/FieldMapperTest.java

@@ -23,6 +23,7 @@ import java.util.function.Predicate;
 import static de.exlll.configlib.Converters.ENUM_CONVERTER;
 import static de.exlll.configlib.Converters.SIMPLE_TYPE_CONVERTER;
 import static de.exlll.configlib.FieldMapperHelpers.*;
+import static de.exlll.configlib.util.CollectionFactory.*;
 import static java.util.stream.Collectors.*;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.*;
@@ -108,7 +109,7 @@ class FieldMapperTest {
 
     @Test
     void instanceFromMapDoesNotSetFinalStaticOrTransientFields() {
-        Map<String, Object> map = Map.of(
+        Map<String, Object> map = mapOf(
                 "staticFinalInt", 10,
                 "staticInt", 10,
                 "finalInt", 10,
@@ -131,7 +132,7 @@ class FieldMapperTest {
         class A {
             LocalTestEnum t = LocalTestEnum.T;
         }
-        Map<String, Object> map = Map.of(
+        Map<String, Object> map = mapOf(
                 "t", "R"
         );
 
@@ -150,7 +151,7 @@ class FieldMapperTest {
         class A {
             TestSubClass c = new TestSubClass();
         }
-        Map<String, Object> map = Map.of("c", Map.of("primInt", 20));
+        Map<String, Object> map = mapOf("c", mapOf("primInt", 20));
 
         A a = new A();
         assertThat(a.c.getPrimInt(), is(0));
@@ -177,8 +178,8 @@ class FieldMapperTest {
         class B {
             LocalTestAbstractClass l = new LocalTestAbstractClassImpl();
         }
-        instanceFromMap(new A(), Map.of("l", Map.of()));
-        instanceFromMap(new B(), Map.of("l", Map.of()));
+        instanceFromMap(new A(), mapOf("l", mapOf()));
+        instanceFromMap(new B(), mapOf("l", mapOf()));
     }
 
 
@@ -255,39 +256,39 @@ class FieldMapperTest {
     void instanceToMapConvertsEnumsContainersToStringContainers() {
         class A {
             @ElementType(LocalTestEnum.class)
-            List<LocalTestEnum> el = List.of(LocalTestEnum.S, LocalTestEnum.T);
+            List<LocalTestEnum> el = listOf(LocalTestEnum.S, LocalTestEnum.T);
             @ElementType(LocalTestEnum.class)
-            Set<LocalTestEnum> es = Set.of(LocalTestEnum.S, LocalTestEnum.T);
+            Set<LocalTestEnum> es = setOf(LocalTestEnum.S, LocalTestEnum.T);
             @ElementType(LocalTestEnum.class)
-            Map<String, LocalTestEnum> em = Map.of(
+            Map<String, LocalTestEnum> em = mapOf(
                     "1", LocalTestEnum.S, "2", LocalTestEnum.T
             );
         }
         Map<String, Object> map = instanceToMap(new A());
-        assertThat(map.get("el"), is(List.of("S", "T")));
-        assertThat(map.get("es"), is(Set.of("S", "T")));
-        assertThat(map.get("em"), is(Map.of("1", "S", "2", "T")));
+        assertThat(map.get("el"), is(listOf("S", "T")));
+        assertThat(map.get("es"), is(setOf("S", "T")));
+        assertThat(map.get("em"), is(mapOf("1", "S", "2", "T")));
     }
 
     @Test
     void instanceFromMapConvertsStringContainersToEnumContainers() {
         class A {
             @ElementType(LocalTestEnum.class)
-            List<LocalTestEnum> el = List.of();
+            List<LocalTestEnum> el = listOf();
             @ElementType(LocalTestEnum.class)
-            Set<LocalTestEnum> es = Set.of();
+            Set<LocalTestEnum> es = setOf();
             @ElementType(LocalTestEnum.class)
-            Map<String, LocalTestEnum> em = Map.of();
+            Map<String, LocalTestEnum> em = mapOf();
         }
-        Map<String, Object> map = Map.of(
-                "el", List.of("S", "T"),
-                "es", Set.of("S", "T"),
-                "em", Map.of("1", "S", "2", "T")
+        Map<String, Object> map = mapOf(
+                "el", listOf("S", "T"),
+                "es", setOf("S", "T"),
+                "em", mapOf("1", "S", "2", "T")
         );
         A a = instanceFromMap(new A(), map);
-        assertThat(a.el, is(List.of(LocalTestEnum.S, LocalTestEnum.T)));
-        assertThat(a.es, is(Set.of(LocalTestEnum.S, LocalTestEnum.T)));
-        assertThat(a.em, is(Map.of(
+        assertThat(a.el, is(listOf(LocalTestEnum.S, LocalTestEnum.T)));
+        assertThat(a.es, is(setOf(LocalTestEnum.S, LocalTestEnum.T)));
+        assertThat(a.em, is(mapOf(
                 "1", LocalTestEnum.S, "2", LocalTestEnum.T
         )));
     }
@@ -303,7 +304,7 @@ class FieldMapperTest {
                 .collect(toSet());
         Map<String, Map<String, Object>> subClassMap = t.getSubClassMap()
                 .entrySet().stream()
-                .map(e -> Map.entry(e.getKey(), e.getValue().asMap()))
+                .map(e -> mapEntry(e.getKey(), e.getValue().asMap()))
                 .collect(toMap(Map.Entry::getKey, Map.Entry::getValue));
         assertAll(
                 () -> assertThat(map.get("subClassSet"), is(subClassSet)),
@@ -339,7 +340,7 @@ class FieldMapperTest {
                 );
         Map<Integer, Map<String, Map<String, Object>>> m = t.getSubClassMapsMap()
                 .entrySet().stream()
-                .map(e -> Map.entry(e.getKey(), f.apply(e.getValue())))
+                .map(e -> mapEntry(e.getKey(), f.apply(e.getValue())))
                 .collect(toMap(Map.Entry::getKey, Map.Entry::getValue));
 
         assertThat(map.get("subClassListsList"), is(lists));
@@ -515,7 +516,7 @@ class FieldMapperTest {
         }
 
         ExcludedClass cls = new ExcludedClass();
-        Map<String, Object> map = Map.of("ex", cls);
+        Map<String, Object> map = mapOf("ex", cls);
         A a = instanceFromMap(new A(), map);
         assertThat(a.ex, sameInstance(cls));
     }

ConfigLib-Core/src/test/java/de/exlll/configlib/ReflectTest.java

@@ -9,11 +9,12 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Set;
 
+import static de.exlll.configlib.util.CollectionFactory.setOf;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 
 class ReflectTest {
-    private static final Set<Class<?>> ALL_SIMPLE_TYPES = Set.of(
+    private static final Set<Class<?>> ALL_SIMPLE_TYPES = setOf(
             boolean.class, Boolean.class,
             byte.class, Byte.class,
             char.class, Character.class,

ConfigLib-Core/src/test/java/de/exlll/configlib/ValidatorTest.java

@@ -12,6 +12,9 @@ import java.util.concurrent.ConcurrentSkipListSet;
 import java.util.concurrent.CopyOnWriteArrayList;
 
 import static de.exlll.configlib.FieldMapperHelpers.*;
+import static de.exlll.configlib.util.CollectionFactory.listOf;
+import static de.exlll.configlib.util.CollectionFactory.mapOf;
+import static de.exlll.configlib.util.CollectionFactory.setOf;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 
@@ -23,7 +26,7 @@ public class ValidatorTest {
             TestSubClass c = new TestSubClass();
         }
 
-        Map<String, Object> map = Map.of(
+        Map<String, Object> map = mapOf(
                 "c", "s"
         );
         String msg = "Initializing field 'c' requires a Map<String, Object> " +
@@ -37,7 +40,7 @@ public class ValidatorTest {
         class A {
             LocalTestEnum t = LocalTestEnum.T;
         }
-        Map<String, Object> map = Map.of(
+        Map<String, Object> map = mapOf(
                 "t", 1
         );
         String msg = "Initializing enum 't' requires a string but '1' is of " +
@@ -51,8 +54,8 @@ public class ValidatorTest {
             TestSubClass c = new TestSubClass();
         }
 
-        Map<String, Object> map = Map.of(
-                "c", Map.of(1, 200, "string", "s")
+        Map<String, Object> map = mapOf(
+                "c", mapOf(1, 200, "string", "s")
         );
         String msg = "Initializing field 'c' requires a Map<String, Object> " +
                 "but the given map contains non-string keys." +
@@ -68,7 +71,7 @@ public class ValidatorTest {
         }
         Map<String, Object> m1 = new HashMap<>();
         m1.put(null, "null");
-        Map<String, Object> m2 = Map.of("c", m1);
+        Map<String, Object> m2 = mapOf("c", m1);
         String msg = "Initializing field 'c' requires a Map<String, Object> " +
                 "but the given map contains non-string keys." +
                 "\nAll entries: {null=null}";
@@ -80,7 +83,7 @@ public class ValidatorTest {
         class A {
             Sub3 s = new Sub3(1);
         }
-        Map<String, Object> map = Map.of("s", Map.of());
+        Map<String, Object> map = mapOf("s", mapOf());
         String msg = "Type 'Sub3' of field 's' doesn't have a no-args constructor.";
         assertIfmCfgExceptionMessage(new A(), map, msg);
     }
@@ -90,7 +93,7 @@ public class ValidatorTest {
         class A {
             Sub1 s = new Sub1();
         }
-        Map<String, Object> map = Map.of("s", Map.of());
+        Map<String, Object> map = mapOf("s", mapOf());
         String msg = "Type 'Sub1' of field 's' is not annotated " +
                 "as a configuration element.";
         assertIfmCfgExceptionMessage(new A(), map, msg);
@@ -107,17 +110,17 @@ public class ValidatorTest {
         class C {
             ConcurrentHashMap<?, ?> m = new ConcurrentHashMap<>();
         }
-        Map<String, Object> m = Map.of("l", List.of("s"));
+        Map<String, Object> m = mapOf("l", listOf("s"));
         String msg = "Can not set field 'l' with type 'CopyOnWriteArrayList' " +
                 "to 'List1'.";
         assertIfmCfgExceptionMessage(new A(), m, msg);
 
-        m = Map.of("s", Set.of("s"));
+        m = mapOf("s", setOf("s"));
         msg = "Can not set field 's' with type 'ConcurrentSkipListSet' " +
                 "to 'Set1'.";
         assertIfmCfgExceptionMessage(new B(), m, msg);
 
-        m = Map.of("m", Map.of(1, "s"));
+        m = mapOf("m", mapOf(1, "s"));
         msg = "Can not set field 'm' with type 'ConcurrentHashMap' " +
                 "to 'Map1'.";
         assertIfmCfgExceptionMessage(new C(), m, msg);
@@ -139,7 +142,7 @@ public class ValidatorTest {
         class A {
             String string;
         }
-        Map<String, Object> map = Map.of("string", "s");
+        Map<String, Object> map = mapOf("string", "s");
         String msg = "The value of field 'string' is null.\n" +
                 "Please assign a non-null default value or remove this field.";
         assertIfmCfgExceptionMessage(new A(), map, msg);
@@ -148,13 +151,13 @@ public class ValidatorTest {
     @Test
     void instanceToMapRequiresListsWithoutElementTypeToContainSimpleTypes() {
         class A {
-            List<TestSubClass> l = new ArrayList<>(List.of(
+            List<TestSubClass> l = new ArrayList<>(listOf(
                     TestSubClass.of(1, "1")
             ));
         }
         class B {
-            List<Set<Map<Integer, TestSubClass>>> l = new ArrayList<>(List.of(
-                    Set.of(Map.of(1, TestSubClass.of(1, "1")))
+            List<Set<Map<Integer, TestSubClass>>> l = new ArrayList<>(listOf(
+                    setOf(mapOf(1, TestSubClass.of(1, "1")))
             ));
         }
 
@@ -174,13 +177,13 @@ public class ValidatorTest {
     @Test
     void instanceToMapRequiresSetsWithoutElementTypeToContainSimpleTypes() {
         class A {
-            Set<TestSubClass> s = new HashSet<>(Set.of(
+            Set<TestSubClass> s = new HashSet<>(setOf(
                     TestSubClass.of(1, "1")
             ));
         }
         class B {
-            Set<List<Map<Integer, TestSubClass>>> s = new HashSet<>(Set.of(
-                    List.of(Map.of(1, TestSubClass.of(1, "1")))
+            Set<List<Map<Integer, TestSubClass>>> s = new HashSet<>(setOf(
+                    listOf(mapOf(1, TestSubClass.of(1, "1")))
             ));
         }
 
@@ -200,13 +203,13 @@ public class ValidatorTest {
     @Test
     void instanceToMapRequiresMapsWithoutElementTypeToContainSimpleTypes() {
         class A {
-            Map<Integer, TestSubClass> m = new HashMap<>(Map.of(
+            Map<Integer, TestSubClass> m = new HashMap<>(mapOf(
                     1, TestSubClass.of(1, "1")
             ));
         }
         class B {
-            Map<Integer, Set<List<TestSubClass>>> m = new HashMap<>(Map.of(
-                    1, Set.of(List.of(TestSubClass.of(1, "1")))
+            Map<Integer, Set<List<TestSubClass>>> m = new HashMap<>(mapOf(
+                    1, setOf(listOf(TestSubClass.of(1, "1")))
             ));
         }
 
@@ -395,7 +398,7 @@ public class ValidatorTest {
             Sub2 s = new Sub2();
         }
 
-        Map<String, Object> map = Map.of("s", Collections.emptyMap());
+        Map<String, Object> map = mapOf("s", Collections.emptyMap());
 
         assertThat(instanceToMap(new B()), is(map));
 
@@ -426,7 +429,7 @@ public class ValidatorTest {
             @ElementType(LocalTestEnum.class)
             List<LocalTestEnum> l = new ArrayList<>();
         }
-        Map<String, Object> m = Map.of("l", List.of());
+        Map<String, Object> m = mapOf("l", listOf());
 
         String msg = "The element type of field 'l' must be a concrete class " +
                 "but type 'LocalTestInterface' is an interface.";
@@ -494,17 +497,17 @@ public class ValidatorTest {
         String msg = "Field 's' is annotated with the ElementType annotation but " +
                 "is not a List, Set or Map.";
         assertItmCfgExceptionMessage(new A(), msg);
-        assertIfmCfgExceptionMessage(new A(), Map.of("s", ""), msg);
+        assertIfmCfgExceptionMessage(new A(), mapOf("s", ""), msg);
     }
 
     @Test
     void instanceFromMapsRequiresElementTypeToBeEnumType() {
         class A {
             @ElementType(TestSubClass.class)
-            List<List<TestSubClass>> l = List.of();
+            List<List<TestSubClass>> l = listOf();
         }
-        Map<String, Object> map = Map.of(
-                "l", List.of(List.of("Q", "V"))
+        Map<String, Object> map = mapOf(
+                "l", listOf(listOf("Q", "V"))
         );
         ConfigurationException ex = assertIfmThrowsCfgException(new A(), map);
         Throwable cause = ex.getCause();
@@ -517,10 +520,10 @@ public class ValidatorTest {
     void instanceFromMapElementConverterRequiresObjectsOfTypeMapStringObject() {
         class A {
             @ElementType(TestSubClass.class)
-            List<List<TestSubClass>> l = List.of();
+            List<List<TestSubClass>> l = listOf();
         }
-        Map<String, Object> map = Map.of(
-                "l", List.of(List.of(1, 2))
+        Map<String, Object> map = mapOf(
+                "l", listOf(listOf(1, 2))
         );
         ConfigurationException ex = assertIfmThrowsCfgException(new A(), map);
         Throwable cause = ex.getCause();

ConfigLib-Core/src/test/java/de/exlll/configlib/classes/TestClass.java

@@ -10,6 +10,8 @@ import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.*;
 
+import static de.exlll.configlib.util.CollectionFactory.listOf;
+import static de.exlll.configlib.util.CollectionFactory.mapOf;
 import static java.util.stream.Collectors.toCollection;
 
 @SuppressWarnings("FieldCanBeLocal")
@@ -44,13 +46,13 @@ public final class TestClass extends YamlConfiguration {
         TEST_VALUES.subClass = TestSubClass.TEST_VALUES;
         /* containers of simple types */
         TEST_VALUES.ints = linkedHashSetOf(1, 2, 3);
-        TEST_VALUES.strings = List.of("a", "b", "c");
+        TEST_VALUES.strings = listOf("a", "b", "c");
         TEST_VALUES.doubleByBool = linkedHashMap(true, 1.0, false, 2.0);
         /* containers of other types */
         TEST_VALUES.subClassSet = linkedHashSetOf(
                 TestSubClass.of(1, "1"), TestSubClass.of(2, "2")
         );
-        TEST_VALUES.subClassList = List.of(
+        TEST_VALUES.subClassList = listOf(
                 TestSubClass.of(1, "1"), TestSubClass.of(2, "2")
         );
         TEST_VALUES.subClassMap = linkedHashMap(
@@ -58,28 +60,28 @@ public final class TestClass extends YamlConfiguration {
                 "2", TestSubClass.of(2, "2")
         );
         /* nested containers of simple types */
-        TEST_VALUES.listsList = List.of(
-                List.of(1, 2), List.of(3, 4)
+        TEST_VALUES.listsList = listOf(
+                listOf(1, 2), listOf(3, 4)
         );
         TEST_VALUES.setsSet = linkedHashSetOf(
                 linkedHashSetOf("a", "b"), linkedHashSetOf("c", "d")
         );
         TEST_VALUES.mapsMap = linkedHashMap(
-                1, Map.of("1", 1), 2, Map.of("2", 2)
+                1, mapOf("1", 1), 2, mapOf("2", 2)
         );
         /* nested containers of custom types */
-        TEST_VALUES.subClassListsList = List.of(
-                List.of(TestSubClass.of(1, "1"), TestSubClass.of(2, "2"))
+        TEST_VALUES.subClassListsList = listOf(
+                listOf(TestSubClass.of(1, "1"), TestSubClass.of(2, "2"))
         );
         TEST_VALUES.subClassSetsSet = linkedHashSetOf(linkedHashSetOf(
                 TestSubClass.of(1, "1"), TestSubClass.of(2, "2")
         ));
         TEST_VALUES.subClassMapsMap = linkedHashMap(
-                1, Map.of("1", TestSubClass.of(1, "2")),
-                2, Map.of("2", TestSubClass.of(2, "2"))
+                1, mapOf("1", TestSubClass.of(1, "2")),
+                2, mapOf("2", TestSubClass.of(2, "2"))
         );
         TEST_VALUES.e1 = TestEnum.NON_DEFAULT;
-        TEST_VALUES.enums = List.of(TestEnum.DEFAULT, TestEnum.NON_DEFAULT);
+        TEST_VALUES.enums = listOf(TestEnum.DEFAULT, TestEnum.NON_DEFAULT);
         TEST_VALUES.converterSubClass = TestSubClass.of(2, "2");
         TEST_VALUES.excludedClass = TestExcludedClass.TEST_VALUES;
     }

ConfigLib-Core/src/test/java/de/exlll/configlib/classes/TestSubClass.java

@@ -4,6 +4,8 @@ import de.exlll.configlib.annotation.ConfigurationElement;
 
 import java.util.Map;
 
+import static de.exlll.configlib.util.CollectionFactory.mapOf;
+
 @SuppressWarnings("FieldCanBeLocal")
 @ConfigurationElement
 public final class TestSubClass {
@@ -27,7 +29,7 @@ public final class TestSubClass {
     }
 
     public Map<String, Object> asMap() {
-        return Map.of("primInt", primInt, "string", string);
+        return mapOf("primInt", primInt, "string", string);
     }
 
     public int getFinalInt() {

ConfigLib-Core/src/test/java/de/exlll/configlib/configs/yaml/YamlConfigurationTest.java

@@ -13,8 +13,8 @@ import java.io.IOException;
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.List;
 
+import static de.exlll.configlib.util.CollectionFactory.listOf;
 import static java.util.stream.Collectors.joining;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;
@@ -129,8 +129,8 @@ class YamlConfigurationTest {
             }
         }
         YamlProperties properties = YamlProperties.builder()
-                .setPrependedComments(List.of("AB", "", "CD"))
-                .setAppendedComments(List.of("AB", "", "CD"))
+                .setPrependedComments(listOf("AB", "", "CD"))
+                .setAppendedComments(listOf("AB", "", "CD"))
                 .build();
         new A(properties).save();
         assertThat(readConfig(testPath), is(PRE_AND_APPENDED_COMMENTS_YML));

ConfigLib-Core/src/test/java/de/exlll/configlib/configs/yaml/YamlSourceTest.java

@@ -11,8 +11,8 @@ import java.io.IOException;
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Map;
 
+import static de.exlll.configlib.util.CollectionFactory.mapOf;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
 
@@ -36,7 +36,7 @@ class YamlSourceTest {
         YamlSource source = new YamlSource(configPath, YamlProperties.DEFAULT);
         Path parentDir = configPath.getParent();
         assertThat(Files.exists(parentDir), is(false));
-        source.saveConfiguration(new TestClass(configPath), Map.of());
+        source.saveConfiguration(new TestClass(configPath), mapOf());
         assertThat(Files.exists(parentDir), is(true));
     }
 }

ConfigLib-Core/src/test/java/de/exlll/configlib/util/CollectionFactory.java

@@ -0,0 +1,79 @@
+package de.exlll.configlib.util;
+
+import java.util.*;
+
+public final class CollectionFactory {
+
+    private CollectionFactory() { throw new AssertionError(); }
+
+    @SafeVarargs
+    public static <T> List<T> listOf(T... values) {
+        return Arrays.asList(values);
+    }
+
+    @SafeVarargs
+    public static <T> Set<T> setOf(T... values) {
+        return new HashSet<>(Arrays.asList(values));
+    }
+
+    public static <K, V> Map<K, V> mapOf() {
+        return new HashMap<>();
+    }
+
+    public static <K, V> Map<K, V> mapOf(K k, V v) {
+        HashMap<K, V> map = new HashMap<>();
+        map.put(k, v);
+        return map;
+    }
+
+    public static <K, V> Map<K, V> mapOf(K k1, V v1, K k2, V v2) {
+        Map<K, V> map = mapOf(k1, v1);
+        map.put(k2, v2);
+        return map;
+    }
+
+    public static <K, V> Map<K, V> mapOf(K k1, V v1, K k2, V v2, K k3, V v3) {
+        Map<K, V> map = mapOf(k1, v1, k2, v2);
+        map.put(k3, v3);
+        return map;
+    }
+
+    public static <K, V> Map<K, V> mapOf(
+            K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4
+    ) {
+        Map<K, V> map = mapOf(k1, v1, k2, v2, k3, v3);
+        map.put(k4, v4);
+        return map;
+    }
+
+    public static <K, V> Map.Entry<K, V> mapEntry(K k, V v) {
+        return new MapEntry<>(k, v);
+    }
+
+    private static final class MapEntry<K, V> implements Map.Entry<K, V> {
+        private final K key;
+        private V value;
+
+        public MapEntry(K key, V value) {
+            this.key = key;
+            this.value = value;
+        }
+
+        @Override
+        public K getKey() {
+            return key;
+        }
+
+        @Override
+        public V getValue() {
+            return value;
+        }
+
+        @Override
+        public V setValue(V value) {
+            V old = this.value;
+            this.value = value;
+            return old;
+        }
+    }
+}

README.md

@@ -430,14 +430,14 @@ public final class DatabasePlugin extends JavaPlugin {
 <dependency>
     <groupId>de.exlll</groupId>
     <artifactId>configlib-bukkit</artifactId>
-    <version>2.0.0</version>
+    <version>2.0.1</version>
 </dependency>
 
 <!-- for Bungee plugins -->
 <dependency>
     <groupId>de.exlll</groupId>
     <artifactId>configlib-bungee</artifactId>
-    <version>2.0.0</version>
+    <version>2.0.1</version>
 </dependency>
 ```
 #### Gradle
@@ -449,9 +449,9 @@ repositories {
 }
 dependencies {
     // for Bukkit plugins
-    compile group: 'de.exlll', name: 'configlib-bukkit', version: '2.0.0'
+    compile group: 'de.exlll', name: 'configlib-bukkit', version: '2.0.1'
 
     // for Bungee plugins
-    compile group: 'de.exlll', name: 'configlib-bungee', version: '2.0.0'
+    compile group: 'de.exlll', name: 'configlib-bungee', version: '2.0.1'
 }
 ```

build.gradle

@@ -1,10 +1,13 @@
 allprojects {
     group 'de.exlll'
-    version '2.0.0'
+    version '2.0.1'
 }
 subprojects {
     apply plugin: 'java'
 
+    sourceCompatibility = 1.8
+    targetCompatibility = 1.8
+
     repositories { mavenCentral() }
 
     dependencies {