From: Jan Lahoda <###@###.###>

I have a question regarding
javax.lang.model.type.TypeVariable.getUpperBound(): it says that if
there are multiple upper bounds specified, the result is DeclaredType
which Types.directSupertypes are the specified bounds. But, is there is
way to detect if the returned DeclaredType is such a compound type (so
that I should call directSupertypes to find out the correct bounds)?
I think we need a Types.isCompound method.