public boolean isSymmetric() {
        return symmetric;
    }
Returns if this operation is symmetric with respect to its parameters.
More formally returns true if: A oper B is true if and only if B oper A is
true.

@return if this operation is symmetric with respect to its parameters
runtime-parent/runtime-join/src/main/java/com/speedment/runtime/join/stage/JoinOperator.java