Target properties with collection getter are not properly recognized

[filiphr]

As originally created by @OlliL in #216. Target properties with collections getters are not properly handled.

They are there in the auto completion:

However, their type is missing. If there was a setter it would have looked like:

Additionally, the getter method is not referenced by the Mapping#target

This means that clicking on the value in the target does not navigate to the method and find usages of the method do not return the annotation.

More information is also in #216

[filiphr]

As part of this we are also fixing #216 (comment)