Avoid classloading deadlock in ValuesSource. (#22994)

Closes #22952

Author: jpountz

core/src/main/java/org/elasticsearch/search/aggregations/support/AggregationContext.java

@@ -77,7 +77,7 @@ public <VS extends ValuesSource> VS valuesSource(ValuesSourceConfig<VS> config,
             } else if (ValuesSource.class.isAssignableFrom(config.valueSourceType)
                     || ValuesSource.Bytes.class.isAssignableFrom(config.valueSourceType)
                     || ValuesSource.Bytes.WithOrdinals.class.isAssignableFrom(config.valueSourceType)) {
-                vs = (VS) ValuesSource.Bytes.EMPTY;
+                vs = (VS) ValuesSource.Bytes.WithOrdinals.EMPTY;
             } else {
                 throw new SearchParseException(searchContext, "Can't deal with unmapped ValuesSource type " + config.valueSourceType, null);
             }

core/src/main/java/org/elasticsearch/search/aggregations/support/ValuesSource.java

@@ -63,25 +63,6 @@ public boolean needsScores() {
 
     public static abstract class Bytes extends ValuesSource {
 
-        public static final WithOrdinals EMPTY = new WithOrdinals() {
-
-            @Override
-            public RandomAccessOrds ordinalsValues(LeafReaderContext context) {
-                return DocValues.emptySortedSet();
-            }
-
-            @Override
-            public RandomAccessOrds globalOrdinalsValues(LeafReaderContext context) {
-                return DocValues.emptySortedSet();
-            }
-
-            @Override
-            public SortedBinaryDocValues bytesValues(LeafReaderContext context) throws IOException {
-                return org.elasticsearch.index.fielddata.FieldData.emptySortedBinary(context.reader().maxDoc());
-            }
-
-        };
-
         @Override
         public Bits docsWithValue(LeafReaderContext context) throws IOException {
             final SortedBinaryDocValues bytes = bytesValues(context);
@@ -94,6 +75,25 @@ public Bits docsWithValue(LeafReaderContext context) throws IOException {
 
         public static abstract class WithOrdinals extends Bytes {
 
+            public static final WithOrdinals EMPTY = new WithOrdinals() {
+
+                @Override
+                public RandomAccessOrds ordinalsValues(LeafReaderContext context) {
+                    return DocValues.emptySortedSet();
+                }
+
+                @Override
+                public RandomAccessOrds globalOrdinalsValues(LeafReaderContext context) {
+                    return DocValues.emptySortedSet();
+                }
+
+                @Override
+                public SortedBinaryDocValues bytesValues(LeafReaderContext context) throws IOException {
+                    return org.elasticsearch.index.fielddata.FieldData.emptySortedBinary(context.reader().maxDoc());
+                }
+
+            };
+
             @Override
             public Bits docsWithValue(LeafReaderContext context) {
                 final RandomAccessOrds ordinals = ordinalsValues(context);