When locating matches on class files the method and fields are not
searched for which result in loosing usages in method declarations and
variable declarations.

Change-Id: I7afcbb9e3c6d2508453bb14171acaf4c58d28db7
Signed-off-by: Gayan Perera <gayanper@gmail.com>
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/185487
Tested-by: JDT Bot <jdt-bot@eclipse.org>