Update schema mappings inspection to produce more detailed logs for unexpected Java types

[rstoyanchev]

As we inspect GraphQL schema types, we also check the return types of corresponding controller methods (or DataFetchers), and nest if necessary for generic parameters such for reactive/async types, paginated types, list types, etc. We perform some sanity checks and detect cases where something is not expected, but generally cannot reliably guard against any unexpected case. That results in reports with missing fields, like with #674.

We can add more detailed DEBUG level logs when we encounter some unexpected case with corresponding Java types to make it easier to track the root cause. In addition, we can change current checks replacing assertions with DEBUG log messages to avoid hard failures out of the box. The decision for a hard failure is instead deferred to the application with #672.