As part of the upgrade, this commit removes the use of any API that
has been deprecated in 2.9. This includes the config props endpoint's
use of SerializationFeature.WRITE_NULL_MAP_VALUES. This has been
replaced with configuring serialization inclusion to only include
properties with non-null values. This means that all null-valued
properties will no longer be serialized, not just those that are an
entry in a map.
Closes gh-8604
Closes gh-8537
Closes gh-7695
87ebec6838