Address the PR comments

Author: srikanthpadakanti

server/src/main/java/org/opensearch/index/query/TermsQueryBuilder.java

@@ -470,42 +470,7 @@ public static TermsQueryBuilder fromXContent(XContentParser parser) throws IOExc
                     );
                 }
                 fieldName = currentFieldName;
-                // Parse the nested object for termsLookup or query
-                String index = null;
-                String id = null;
-                String path = null;
-
-
-                XContentParser.Token innerToken;
-                String innerFieldName = null;
-                while ((innerToken = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
-                    if (innerToken == XContentParser.Token.FIELD_NAME) {
-                        innerFieldName = parser.currentName();
-                    } else if (innerToken.isValue()) {
-                        if ("index".equals(innerFieldName)) {
-                            index = parser.text();
-                        } else if ("id".equals(innerFieldName)) {
-                            id = parser.text();
-                        } else if ("path".equals(innerFieldName)) {
-                            path = parser.text();
-                        } else {
-                            throw new ParsingException(
-                                parser.getTokenLocation(),
-                                "[" + TermsQueryBuilder.NAME + "] query does not support [" + innerFieldName + "]"
-                            );
-                        }
-                    } else if (innerToken == XContentParser.Token.START_OBJECT && "query".equals(innerFieldName)) {
-                        nestedQuery = AbstractQueryBuilder.parseInnerQueryBuilder(parser);
-                    }
-                }
-
-                if (index != null || id != null || path != null || nestedQuery != null) {
-                    if (path == null) {
-                        throw new ParsingException(parser.getTokenLocation(), "[" + TermsQueryBuilder.NAME + "] missing required field [path]");
-                    }
-                    termsLookup = new TermsLookup(index, id, path, nestedQuery);
-                }
-                //termsLookup = TermsLookup.parseTermsLookup(parser);
+                termsLookup = TermsLookup.parseTermsLookup(parser);
             } else if (token.isValue()) {
                 if (AbstractQueryBuilder.BOOST_FIELD.match(currentFieldName, parser.getDeprecationHandler())) {
                     boost = parser.floatValue();

server/src/main/java/org/opensearch/indices/TermsLookup.java

@@ -66,6 +66,9 @@ public class TermsLookup implements Writeable, ToXContentFragment {
     private String routing;
     private QueryBuilder query;
 
+    public TermsLookup(String index, String id, String path) {
+        this(index, id, path, null); // Delegate to the existing constructor
+    }
     public TermsLookup(String index, String id, String path, QueryBuilder query) {
         if (Strings.isEmpty(index)) {
             throw new IllegalArgumentException("index cannot be null or empty for TermsLookup");
@@ -108,8 +111,10 @@ public TermsLookup(StreamInput in) throws IOException {
         if (in.getVersion().onOrAfter(Version.V_2_17_0)) {
             store = in.readBoolean();
         }
-        if (in.readBoolean()) {
-            query = in.readOptionalWriteable(inStream -> inStream.readNamedWriteable(QueryBuilder.class));
+        if (in.getVersion().onOrAfter(Version.V_3_0_0)) {
+            if (in.readBoolean()) {
+                query = in.readOptionalWriteable(inStream -> inStream.readNamedWriteable(QueryBuilder.class));
+            }
         }
     }
 
@@ -125,12 +130,7 @@ public void writeTo(StreamOutput out) throws IOException {
         if (out.getVersion().onOrAfter(Version.V_2_17_0)) {
             out.writeBoolean(store);
         }
-        if (query != null) {
-            out.writeBoolean(true);
-            out.writeOptionalWriteable(query);
-        } else {
-            out.writeBoolean(false);
-        }
+        out.writeOptionalWriteable(query);
     }
 
     public String path() {
@@ -181,18 +181,10 @@ public TermsLookup id(String id) {
         String path = (String) args[2];
         QueryBuilder query = (QueryBuilder) args[3]; // Optional query
 
-        // Ensure either `id` or `query` is provided, but not both
-        if (id == null && query == null) {
-            throw new IllegalArgumentException("[" + TermsQueryBuilder.NAME + "] query lookup element requires specifying either the id or the query.");
-        }
-        if (id != null && query != null) {
-            throw new IllegalArgumentException("[" + TermsQueryBuilder.NAME + "] query lookup element cannot specify both id and query.");
-        }
         return new TermsLookup(index, id, path, query);
     });
     static {
         PARSER.declareString(constructorArg(), new ParseField("index")); // Required
-        //PARSER.declareString(constructorArg(), new ParseField("id")); // Optional
         PARSER.declareString(optionalConstructorArg(), new ParseField("id")); // Optional
         PARSER.declareString(constructorArg(), new ParseField("path")); // Required
         PARSER.declareObject(optionalConstructorArg(), (parser, context) -> {