Summary
-------

Update notes in `ParameterizedType.getRawType()` about core reflection implementation always returning a `Class` and the rationale for a `Type` return type.

Problem
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All `ParameterizedType` instances created by core reflection return a `Class` for `ParameterizedType.getRawType()`, yet this is not described in any documentation and is confusing to users.

Solution
--------

Add a note that `ParameterizedType.getRawType()` always return a `Class` for core reflection `ParameterizedType` objects, and that external implementations (such as those modeling unloaded types) can return other `Type` implementations modeling classes and interfaces.

Specification
-------------

    --- a/src/java.base/share/classes/java/lang/reflect/ParameterizedType.java
    +++ b/src/java.base/share/classes/java/lang/reflect/ParameterizedType.java
    @@ -66,11 +66,16 @@ public interface ParameterizedType extends Type {
         Type[] getActualTypeArguments();
     
         /**
    -     * Returns the {@code Type} object representing the class or interface
    -     * that declared this type.
    +     * {@return the {@code Type} object representing the class or interface
    +     * that declared this type}
    +     *
    +     * @apiNote
    +     * Returns a {@link Class} object for all {@code ParameterizedType}
    +     * objects from core reflection, which models types in this running VM.
    +     * The return type is {@code Type} because {@code ParameterizedType}
    +     * objects from other implementations may represent types not in
    +     * this running VM.
          *
    -     * @return the {@code Type} object representing the class or interface
    -     *     that declared this type
          * @since 1.5
          */
         Type getRawType();