@Override
  protected java.lang.Object standardSchemeReadValue(org.apache.thrift.protocol.TProtocol iprot, org.apache.thrift.protocol.TField field) throws org.apache.thrift.TException {
    _Fields setField = _Fields.findByThriftId(field.id);
    if (setField != null) {
      switch (setField) {
        case NAMES:
          if (field.type == NAMES_FIELD_DESC.type) {
            java.util.List<java.lang.String> names;
            {
              org.apache.thrift.protocol.TList _list682 = iprot.readListBegin();
              names = new java.util.ArrayList<java.lang.String>(_list682.size);
              @org.apache.thrift.annotation.Nullable java.lang.String _elem683;
              for (int _i684 = 0; _i684 < _list682.size; ++_i684)
              {
                _elem683 = iprot.readString();
                names.add(_elem683);
              }
              iprot.readListEnd();
            }
            return names;
          } else {
            org.apache.thrift.protocol.TProtocolUtil.skip(iprot, field.type);
            return null;
          }
        case EXPRS:
          if (field.type == EXPRS_FIELD_DESC.type) {
            java.util.List<DropPartitionsExpr> exprs;
            {
              org.apache.thrift.protocol.TList _list685 = iprot.readListBegin();
              exprs = new java.util.ArrayList<DropPartitionsExpr>(_list685.size);
              @org.apache.thrift.annotation.Nullable DropPartitionsExpr _elem686;
              for (int _i687 = 0; _i687 < _list685.size; ++_i687)
              {
                _elem686 = new DropPartitionsExpr();
                _elem686.read(iprot);
                exprs.add(_elem686);
              }
              iprot.readListEnd();
            }
            return exprs;
          } else {
            org.apache.thrift.protocol.TProtocolUtil.skip(iprot, field.type);
            return null;
          }
        default:
          throw new java.lang.IllegalStateException("setField wasn't null, but didn't match any of the case statements!");
      }
    } else {
      org.apache.thrift.protocol.TProtocolUtil.skip(iprot, field.type);
      return null;
    }
  }
Find the _Fields constant that matches name, or null if its not found.
standalone-metastore/metastore-common/src/gen/thrift/gen-javabean/org/apache/hadoop/hive/metastore/api/RequestPartsSpec.java