@Override
        public final boolean equals(Object o) {
            if (this == o) return true;
            if (!(o instanceof UnaryExpression)) return false;
            final UnaryExpression<?, ?> that = (UnaryExpression<?, ?>) o;
            return Objects.equals(inner(), that.inner())
                && Objects.equals(operator(), that.operator());
        }
Internal base implementation for a sign-operation.

@param <T>      the input entity type
@param <INNER>  the inner expression type
runtime-parent/runtime-compute/src/main/java/com/speedment/runtime/compute/internal/expression/SignUtil.java