Fixed nondetermistic tests in MappingRedisConverterUnitTests.

[EdwinIngJ]

Fixes #3241

Summary

For the tests:

• org.springframework.data.redis.core.convert.MappingRedisConverterUnitTests.writeShouldWritePartialUpdatePathWithRegisteredCustomConversionCorrectly
• org.springframework.data.redis.core.convert.MappingRedisConverterUnitTests.writeShouldHonorCustomConversionOnNestedType

An ObjectMapper was used to parse the JSON string and expected JSON string, enabling the assertion to test for equality while being insensitive to property ordering.

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[EdwinIngJ]

I also found a similar issue with org.springframework.data.redis.core.convert.MappingRedisConverterUnitTests.writeShouldHonorCustomConversionOnRootType. I could update this PR with the fix or open a new PR.

[mp911de]

Thank you for your pull request. Closing this one in favor of a simpler approach.