Implement missing prepareSeekExact methods for TermsEnum

In apache/lucene#13359 a new "prepareSeekExact" method
was added that can improve seeking on TermsEnum implementations. Two of our own
subclasses of TermsEnum don't seem to support seeking for text, so we can safely
throw an UOE there. The third (FilterableTermsEnum) changes to simple returning
a Supplier for the actual "seek" method for now.

server/src/main/java/org/elasticsearch/common/lucene/index/FilterableTermsEnum.java

@@ -26,6 +26,7 @@
 import org.apache.lucene.util.BitSet;
 import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.IOBooleanSupplier;
 import org.elasticsearch.core.Nullable;
 
 import java.io.IOException;
@@ -61,7 +62,7 @@ static class Holder {
     protected BytesRef current;
     protected final int docsEnumFlag;
 
-    public FilterableTermsEnum(IndexReader reader, String field, int docsEnumFlag, @Nullable Query filter) throws IOException {
+    public FilterableTermsEnum(IndexReader reader, String field, int docsEnumFlag, @Nullable Query f) throws IOException {
         if ((docsEnumFlag != PostingsEnum.FREQS) && (docsEnumFlag != PostingsEnum.NONE)) {
             throw new IllegalArgumentException("invalid docsEnumFlag of " + docsEnumFlag);
         }
@@ -176,6 +177,11 @@ public boolean seekExact(BytesRef text) throws IOException {
         }
     }
 
+    @Override
+    public IOBooleanSupplier prepareSeekExact(BytesRef bytesRef) {
+        return () -> this.seekExact(bytesRef);
+    }
+
     @Override
     public int docFreq() throws IOException {
         return currentDocFreq;

server/src/main/java/org/elasticsearch/index/mapper/flattened/FlattenedFieldMapper.java

@@ -27,6 +27,7 @@
 import org.apache.lucene.search.SortField;
 import org.apache.lucene.util.AttributeSource;
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.IOBooleanSupplier;
 import org.apache.lucene.util.automaton.Automata;
 import org.apache.lucene.util.automaton.Automaton;
 import org.apache.lucene.util.automaton.CompiledAutomaton;
@@ -459,6 +460,11 @@ public AttributeSource attributes() {
             throw new UnsupportedOperationException();
         }
 
+        @Override
+        public IOBooleanSupplier prepareSeekExact(BytesRef bytesRef) throws IOException {
+            throw new UnsupportedOperationException();
+        }
+
         @Override
         public boolean seekExact(BytesRef text) throws IOException {
             throw new UnsupportedOperationException();

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/termsenum/action/SimpleTermCountEnum.java

@@ -13,6 +13,7 @@
 import org.apache.lucene.index.TermsEnum;
 import org.apache.lucene.util.AttributeSource;
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.IOBooleanSupplier;
 import org.elasticsearch.index.mapper.MappedFieldType;
 
 import java.io.IOException;
@@ -69,6 +70,11 @@ public AttributeSource attributes() {
         throw new UnsupportedOperationException();
     }
 
+    @Override
+    public IOBooleanSupplier prepareSeekExact(BytesRef bytesRef) throws IOException {
+        throw new UnsupportedOperationException();
+    }
+
     @Override
     public boolean seekExact(BytesRef text) throws IOException {
         throw new UnsupportedOperationException();