code: public boolean has(String tableName, String columnName) {
  		return has(EXTENSION_NAME, tableName, columnName)
  				&& connection.tableExists(getRTreeTableName(tableName,
  						columnName));
  	}
docs: Determine if the GeoPackage table and column has the extension
  
  @param tableName
  table name
  @param columnName
  column name
  @return true if has extension