private static Schema schema(Properties props) {
    String schemaString = props.getProperty(InputFormatConfig.TABLE_SCHEMA);
    Preconditions.checkNotNull(schemaString, "Table schema not set");
    return SchemaParser.fromJson(schemaString);
  }
Parse the table schema from the properties
@param props the controlling properties
@return schema instance
iceberg/iceberg-handler/src/main/java/org/apache/iceberg/mr/Catalogs.java