What's the purpose of fromReflectedMethod and toReflectedMethod in JNI?

I was reading the JNI spec and saw the reflection support methods section.

I don't quite understand what they are used for or what's the intended purpose. Since method ID is looked up using name and signature, don't we already have that information? And if we want to get more details, we can always write a java wrapper. So that cannot be the purpose I thought.