@Override
    public FieldIsNotNullPredicate<ENTITY, T> isNotNull() {
        return new MapperIsNotNull<>(this, field);
    }
Abstract base implementation of {@link FieldMapper}.

@author Emil Forslund
@since  3.1.0
runtime-parent/runtime-field/src/main/java/com/speedment/runtime/field/internal/expression/AbstractFieldMapper.java