be a functional interface"

Reduced fix for bug 573933 only to case where targetType is instanceof
ParameterizedTypeBinding. The new test case from bug 576152 covers the
case where it can be ArrayBinding.

Change-Id: Iabb6d224b24890f8f9745a1055ad5393d5536f1c
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/185699
Tested-by: JDT Bot <jdt-bot@eclipse.org>
Reviewed-by: Jay Arthanareeswaran <jarthana@in.ibm.com>
Reviewed-by: Andrey Loskutov <loskutov@gmx.de>