protected void checkBuildable(String defaultConstraintName, Configuration conf)
      throws MetaException {
    if (tableName == null || columns.isEmpty()) {
      throw new MetaException("You must provide table name and columns");
    }
    if (constraintName == null) {
      constraintName = tableName + "_" + defaultConstraintName;
    }
    if (catName == null) catName = MetaStoreUtils.getDefaultCatalog(conf);
  }
Base builder for all types of constraints.  Database name, table name, and column name
must be provided.
@param <T> Type of builder extending this.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/client/builder/ConstraintBuilder.java