code: protected UserCustomTable getRTreeTable(FeatureTable featureTable) {
  
  		List<UserCustomColumn> columns = new ArrayList<>();
  		columns.add(UserCustomColumn.createPrimaryKeyColumn(0, COLUMN_ID));
  		columns.add(UserCustomColumn.createColumn(1, COLUMN_MIN_X,
  				GeoPackageDataType.FLOAT, false, null));
  		columns.add(UserCustomColumn.createColumn(2, COLUMN_MAX_X,
  				GeoPackageDataType.FLOAT, false, null));
  		columns.add(UserCustomColumn.createColumn(3, COLUMN_MIN_Y,
  				GeoPackageDataType.FLOAT, false, null));
  		columns.add(UserCustomColumn.createColumn(4, COLUMN_MAX_Y,
  				GeoPackageDataType.FLOAT, false, null));
  
  		String rTreeTableName = getRTreeTableName(featureTable.getTableName(),
  				featureTable.getGeometryColumn().getName());
  
  		UserCustomTable userCustomTable = new UserCustomTable(rTreeTableName,
  				columns);
  
  		return userCustomTable;
  	}
docs: Get the RTree Table
  
  @param featureTable
  feature table
  @return RTree table