question: protected void deleteSessionVariables ( String sessionId , String ... varNames ) { if ( sessionId . equals ( "" ) ) { return ; } Key key = keyFactory . newKey ( sessionId ) ; Transaction transaction = datastore . newTransaction ( ) ; try { Entity stateEntity = transaction . get ( key ) ; Entity . Builder builder = Entity . builder ( stateEntity ) ; StringBuilder delNames = new StringBuilder ( ) ; for ( String varName : varNames ) { delNames . append ( varName + " " ) ; builder = builder . remove ( varName ) ; } datastore . update ( builder . build ( ) ) ; } catch ( NullPointerException e ) { } finally { if ( transaction . active ( ) ) { transaction . rollback ( ) ; } } }
target:  Delete a value stored in the project's datastore.