Remove unused and misleading setters on ConfigurationPropertiesBindingPostProcessor

[wilkinsona]

ConfigurationPropertiesBindingPostProcessor currently has a number of setter methods that aren't used by Boot itself and that provide misleading indications of its capabilities. For example, setPropertySources(Iterable<PropertySource> suggests that the property sources can be set at any time. This, however, is not the case as calling the setter will only have an effect up until afterPropertiesSet is called.

The following setter methods should be removed to more accurately reflect the post-processor's capabilities and intended usage:

• setOrder(int)
• setPropertySources(Iterable<PropertySource>
• setValidator(Validator)
• setConversionService(ConversionService)

To give time for adaptation to these changes this issue will deprecate the setters and a separate issue will remove them prior to Boot 2.0 reaching the release candidate phase. See #10460 for a related issue where we're now moving towards Spring Cloud leaving ConfigurationPropertiesBindingPostProcessor alone and using a slightly enhanced ConfigurationPropertiesBinder and its own @RefreshableConfigurationProperties annotation instead.

[snicoll]

@wilkinsona I thought we finally opt for removing those setters right now. Have I misunderstood?

[wilkinsona]

You haven’t misunderstood so I’ve just retitled the issue. At the risk of stating the obvious, we shouldn’t remove anything till #10685 is complete.