Make Java-lite reject unmatched end-group tag.

This brings it into conformance with our spec and other languages.

PiperOrigin-RevId: 702432195

Author: mkruskal-google

conformance/failure_list_java_lite.txt

@@ -6,7 +6,3 @@
 
 Required.*.ProtobufInput.PrematureEofInDelimitedDataForKnownNonRepeatedValue.MESSAGE                               # Should have failed to parse, but didn't.
 Required.*.ProtobufInput.PrematureEofInDelimitedDataForKnownRepeatedValue.MESSAGE                                  # Should have failed to parse, but didn't.
-Required.*.ProtobufInput.UnmatchedEndGroup                                                                         # Should have failed to parse, but didn't.
-Required.*.ProtobufInput.UnmatchedEndGroupUnknown                                                                  # Should have failed to parse, but didn't.
-Required.*.ProtobufInput.UnmatchedEndGroupWithData                                                                 # Should have failed to parse, but didn't.
-Required.*.ProtobufInput.UnmatchedEndGroupWrongType                                                                # Should have failed to parse, but didn't.

java/core/src/main/java/com/google/protobuf/UnknownFieldSchema.java

@@ -93,6 +93,9 @@ final boolean mergeOneFieldFrom(B unknownFields, Reader reader, int currentDepth
         addGroup(unknownFields, fieldNumber, toImmutable(subFields));
         return true;
       case WireFormat.WIRETYPE_END_GROUP:
+        if (currentDepth == 0) {
+          throw InvalidProtocolBufferException.invalidEndTag();
+        }
         return false;
       default:
         throw InvalidProtocolBufferException.invalidWireType();