TYPE_USE annotations on type parameter declarations

[Michael Ernst]

I have a question about use of TYPE_USE annotations on type parameter 
declarations.

I did not expect this code to compile:

    @Target(ElementType.TYPE_USE)
    @interface TU { }

    // This is surprising:
    public class TypeUseAtParameter<@TU T> {
    }

because I thought that a @Target(TYPE_USE) annotation could not be written 
on the declaration of a type parameter.  In fact, javac (from JDK 8 or JDK 
9) accepts it.  See the attachment for a full, compilable test case.

Section 9.6.4.1 says, "There are 16 type contexts (§4.11), all represented 
by the enum constant TYPE_USE of java.lang.annotation.ElementType.", and 
section 4.11 does not include a type parameter declaration as one of these 
locations.

Am I confused, or may there be a problem with javac?

Thanks!

                      -Mike
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import java.lang.annotation.ElementType;
import java.lang.annotation.Target;

@Target(ElementType.TYPE_USE)
@interface TU { }

@Target(ElementType.TYPE_PARAMETER)
@interface TP { }

// This is surprising:
public class TypeUseAtParameter<@TU T> {
}

// This is expected:
class TypeParameterAtParameter<@TP T> {
}