Tags Merging Strategies.

You can provide tags to gestalt in two ways, setting the defaults in the gestalt config and passing in tags when getting a configuration.

Gestalt gestalt = new GestaltBuilder()
.addSource(ClassPathConfigSourceBuilder.builder().setResource("/default.properties").build())  // Load the default property files from resources.
.addSource(FileConfigSourceBuilder.builder().setFile(devFile).setTags(Tags.profile("dev").build()))
.addSource(FileConfigSourceBuilder.builder().setFile(testFile).setTags(Tags.profile("test").build()))
.setDefaultTags(Tags.profile("dev"))
.build();

// will use the Tags.profile("test") and ignore the default tags of Tags.profile("dev"), so it will use values from the testFile.
HttpPool pool = gestalt.getConfig("http.pool", HttpPool.class, Tags.profile("test"));

The default behaviour is to use the provided tags with the getConfig and if not provided, fall back to the defaults.

By passing in the TagMergingStrategy to the GestaltBuilder, you can set your own strategy.

Gestalt gestalt = new GestaltBuilder()
      .addSource(MapConfigSourceBuilder.builder().setCustomConfig(configs).build())
      .addSource(MapConfigSourceBuilder.builder()
          .setCustomConfig(configs2)
          .addTag(Tag.profile("orange"))
          .addTag(Tag.profile("flower"))
          .build())
      .setTagMergingStrategy(new TagMergingStrategyCombine())
      .build();

The available strategies are:

name	Set Theory	Description
TagMergingStrategyFallback	exclusive or	Use the provided tags with getConfig, and if not provided use a default fallback.
TagMergingStrategyCombine	union	Merge the provided tags with getConfig, and the defaults

You can provide your own strategy by implementing TagMergingStrategy.