private void ensureGroupVerticesIsMutable() {
        if (!groupVertices_.isModifiable()) {
          groupVertices_ = new com.google.protobuf.LazyStringArrayList(groupVertices_);
        }
        bitField0_ |= 0x00000002;
      }
<code>optional string group_name = 1;</code>
@param value The bytes for groupName to set.
@return This builder for chaining.
llap-common/src/gen/protobuf/gen-java/org/apache/hadoop/hive/llap/daemon/rpc/LlapDaemonProtocolProtos.java