@Override
    public double applyAsDouble(ENTITY instance) {
        return getter.applyAsDouble(instance);
    }
Default implementation of the {@link GetDouble}-interface.

@param <ENTITY> the entity type
@param <D>      the database type

@author Emil Forslund
@since  3.0.2
runtime-parent/runtime-field/src/main/java/com/speedment/runtime/field/internal/method/GetDoubleImpl.java