RFR: JEP 359-Records: reflection code

[Brian Goetz]

Spec in Class.java:

  - Various {@code RecordComponent} should be {@link RecordComponent}.
  - Rather than say "if this class was declared as a record in the 
source code", instead say "is a record class", since record classes are 
a term defined by the JLS.
  - For isRecord/getRecordComponents, should include "@jls 8.10" link

RecordComponent.java:

  - Add @jls 8.10 link
  - "Returns the name of the component represented by this record 
component." -> "Returns the name of this record component."  and similar 
in other methods.  Since RC models a record component, its clear enough 
what is meant.
  - For getGenericSignature, there should be a link back to @jls or 
@jvms that describes the format of the signature string.
  - Doesn't getAnnotation() need some spec, or an {@inheritDoc}?