Describe the PR

When determining methods/fields by reflection, we could run into situations, that the classes, that are referenced in the methods (e.g. parameter types, return types) are not on the auxclasspath. Then a LinkageError is thrown, which was not handled before.

The reason, why the types are missing on the auxclasspath is actually a valid case: As long as the methods are not used in the code, the referenced classes neither need to be on the compile classpath. And we use the compile classpath as our auxclasspath.

This can happen, if a project uses a provided dependency and this dependency has other transitive dependencies. These transitive dependencies are not on the compile classpath.

This PR fixes the problem in ImportWrapper as well as in two other cases, where we use reflection.

Related issues

• Fixes [java] NoClassDefFoundError on upgrade from 6.25.0 to 6.26.0 #2663

Ready?

• Added unit tests for fixed bug/feature - I only tested it with the integration test from [java] NoClassDefFoundError on upgrade from 6.25.0 to 6.26.0 #2663
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by travis)
• Added (in-code) documentation (if needed)