@Override
        public final int hashCode() {
            return Objects.hash(firstInner, secondInner, operator());
        }
Abstract base for a minus operation that takes a {@code long} as the
second operand.

@param <T>      the input type
@param <INNER>  the first operand expression type
runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/internal/expression/MinusUtil.java