@Override
    public double applyAsDouble(ENTITY object) {
        return mapper.applyAsDouble(field.get(object));
    }
Default implementation of {@link FieldToDouble}.

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