@org.apache.thrift.annotation.Nullable
    public static _Fields findByThriftId(int fieldId) {
      switch(fieldId) {
        case 1: // CAT_NAME
          return CAT_NAME;
        case 2: // DB_NAME
          return DB_NAME;
        case 3: // TABLE_NAME
          return TABLE_NAME;
        case 4: // PARTITIONS
          return PARTITIONS;
        case 5: // ENVIRONMENT_CONTEXT
          return ENVIRONMENT_CONTEXT;
        case 6: // WRITE_ID
          return WRITE_ID;
        case 7: // VALID_WRITE_ID_LIST
          return VALID_WRITE_ID_LIST;
        case 8: // SKIP_COLUMN_SCHEMA_FOR_PARTITION
          return SKIP_COLUMN_SCHEMA_FOR_PARTITION;
        case 9: // PARTITION_COL_SCHEMA
          return PARTITION_COL_SCHEMA;
        default:
          return null;
      }
    }
Find the _Fields constant that matches fieldId, or null if its not found.
standalone-metastore/metastore-common/src/gen/thrift/gen-javabean/org/apache/hadoop/hive/metastore/api/AlterPartitionsRequest.java