Replace Dictionary with ConcurrentDictionary in SerializablePropertyCache

[jar-stripe]

Why?

SerializablePropertyCache (used for System.Text.Json serialization) caches properties and converter instances in a pair of Dictionary objects. #3100 reported a a concurrency related error when they initiated two simultaneous calls to a method that made an API call and serialized the results on return using STJ. This PR fixes this issue by switching the Dictionary objects to thread-safe alternatives and refactoring the cache-building code to also be thread-safe.

What?

• Replaced Dictionary objects with ConcurrentDictionary objects in SerializablePropertyCache
• refactored where we populate the dictionaries to use GetOrAdd, which provides thread-safe access to the value or a callback if the key/value is not set yet.

See Also