Several changes to how objects are initialized inside the template:
1. In one is not specified, a MappingMongoConverter is created and set as the default.
2. A special ApplicationEventPublisher implementation is installed by default to handle creating indexes when the template isn't used inside a Spring application context.
3. If a Spring application context is available, it will be set as the template's application context and eventPublisher, with the index creator being registered as an event listener if one isn't already present.
The tests had to be changed in a couple places to accurately reflect how mapping contexts and converters are now handled.
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