+\r
+ /**\r
+ * Returns expressions selected by their left-hand keys - as in 'expressionField=value'.\r
+ * <p>\r
+ * If the parameter has expressions expr1=x,expr2=y,expr3=z,expr1=u then invoking this method \r
+ * with {"expr1","expr3"} would return expr1=x,expr3=z,expr1=u but not expr2=y. \r
+ * </p>\r
+ * @param expressionFields The expression types to return\r
+ * @return a list of expressions with the given keys to the left of the operator\r
+ * \r
+ */\r