Unbounded cache for function definitions

OOM error is possible while attempting to add infinite amount of functions to Function Registry. Affected Spring Products and Versions: Spring Cloud Function 3.2.x: versions prior to 3.2.16 Spring Cloud Function 4.1.x: versions prior to 4.1.10 Spring Cloud Function 4.2.x: versions prior to 4.2.6 Spring Cloud Function 4.3.x: versions prior to 4.3.3 Spring Cloud Function 5.0.x: versions prior to 5.0.2 Older, unsupported versions are also affected.