Allow conversion of v1-v3 data snapshots

bukkit/src/main/java/net/william278/husksync/util/BukkitLegacyConverter.java

@@ -41,6 +41,7 @@ import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.time.OffsetDateTime;
 import java.util.*;
+import java.util.logging.Level;
 
 public class BukkitLegacyConverter extends LegacyConverter {
 
@@ -55,10 +56,7 @@ public class BukkitLegacyConverter extends LegacyConverter {
         final JSONObject object = new JSONObject(plugin.getDataAdapter().bytesToString(data));
         final int version = object.getInt("format_version");
         if (version != 3) {
-            throw new DataAdapter.AdaptionException(String.format(
-                    "Unsupported legacy data format version: %s. Please downgrade to an earlier version of HuskSync, " +
-                            "perform a manual legacy migration, then attempt to upgrade again.", version
-            ));
+            plugin.log(Level.WARNING, String.format("Converting data from older v2 data format (%s).", version));
         }
 
         // Read legacy data from the JSON object

common/src/main/java/net/william278/husksync/data/DataSnapshot.java

@@ -45,7 +45,7 @@ public class DataSnapshot {
 
     /*
      * Current version of the snapshot data format.
-     * HuskSync v3.0 uses v4; HuskSync v2.0 uses v3. HuskSync v1.0 uses v1 or v2
+     * HuskSync v3.0 uses v4; HuskSync v2.0 uses v1-v3
      */
     protected static final int CURRENT_FORMAT_VERSION = 4;
 
@@ -240,12 +240,6 @@ public class DataSnapshot {
 
     /**
      * Get the format version of the snapshot (indicating the version of HuskSync that created it)
-     * <ul>
-     *     <li>1: HuskSync v1.0+</li>
-     *     <li>2: HuskSync v1.5+</li>
-     *     <li>3: HuskSync v2.0+</li>
-     *     <li>4: HuskSync v3.0+</li>
-     * </ul>
      *
      * @return The format version of the snapshot
      * @since 3.0