Validate that paths are not a subpath of another (bean) property

[ljacqu]

Right now, it's possible to do this:

class Bean {
   String name;
   int length;
}

class Properties implements SettingsHolder {
  public static final Property<Bean> BEAN = new BeanProperty("bean", new Bean());
  // subpath of bean above!
  public static final Property<Integer> LENGTH = new IntegerProperty("bean.length", 5);
}

class Main {
  public void main(String... args) {
    SettingsManager manager = new SettingsManager(resource, null, Properties.class);
    Bean bean = manager.getProperty(Properties.BEAN); // e.g. Bean(name="hi", length=5)
    int length = manager.getProperty(Properties.LENGTH); // 5

    // but now:
    manager.setProperty(Properties.BEAN, new Bean("hello", -1));
    manager.setProperty(Properties.LENGTH, 20);

    // results in inconsistent state (which cannot be exported in a sensible manner):
    manager.getProperty(Properties.BEAN); // returns Bean(name="hello", length=-1)
    manager.getProperty(Properties.LENGTH); // returns 20
  }
}

This can be handled in a few ways:

• somehow keep track of "bean paths" and throw if there is a property like LENGTH which is in a "bean path." Need to keep all paths as we may encounter LENGTH before BEAN. This could be done in ConfigurationDataBuilder, which would work out quite well.
• provide a validation tool that handles this and more. Relies on the user knowing about it and running it to validate his config...
• do nothing concerning this; if such a case happens we just don't guarantee that it works

I like the first point because we could validate in general that there are no path conflicts (for any types, property at path path and a property at path path.subpath are a conflict).

[ljacqu]

Relates to #5

[ljacqu]

Closing as duplicate as by default it cannot happen anymore: PropertyListBuilder checks for overlapping paths