Enable isolation of config properties into a separate POJO

Hi,

i think it would be a nice feature to add another annotation e.g. @ConfigProperties which would allow injecting a group of properties with the same prefix into a separate POJO. This would reduce the amount of @Inject and @ConfigProperty annotations and would allow better usage of the same set of properties across multiple classes.

microprofile-config.properties:

person.data.firstName=John
person.data.lastName=Smith

Example class:

@ConfigProperties(prefix = "person.data")
public class PersonData {
  private String firstName;
  private String lastName;
  ...
}

Referencing PersonData:

public class Person {
  @Inject
  private PersonData personData;
}

[rmannibucau]

Issue with a pojo is you cant do much and actually just stay on the existing features whereas a proxy enables to:

1. Support scopes (which is key here otherwise inconsistencies are trivial to create).
2. Supports additional features (interceptors, caching, reloading etc…)

Getters are then not needed at all and you just used methods, trivial model and efficient 😃

[Emily-Jiang]

Need to reopen this for further update based on some feedback and discussion on the google group mailinglist.