code: private Extensions getOrCreate() {
  
  		// Create table
  		geoPackage.createExtendedRelationsTable();
  
  		Extensions extension = getOrCreate(EXTENSION_NAME,
  				ExtendedRelation.TABLE_NAME, null, EXTENSION_DEFINITION,
  				ExtensionScopeType.READ_WRITE);
  
  		return extension;
  	}
docs: Get or create the extension
  
  @return extension