In the various hint related classes, there's a mixture of using ClassUtils.getDefaultClassLoader() and the hint class's own class loader:

ClassUtils.getDefaultClassLoader(): - ReflectionHints - ObjectToObjectConverterRuntimeHints (delegates to ReflectionHints)

getClass().getClassLoader(): - FilePatternResourceHintsRegistrar - ResourceHints - SpringFactoriesLoaderRuntimeHints

For consistency, I think the same default class loader should be used. My preference would be to use ClassUtils.getDefaultClassLoader().

In addition to the inconsistency across hints classes, it looks like SpringFactoriesLoaderRuntimeHints is inconsistent with SpringFactoriesLoader as the latter will use ClassUtils.getDefaultClassLoader().