Support for arrays as parameters

[andymc12]

Section 3.2 says the following:

Valid parameter types for each of the above annotations are listed in
the corresponding Javadoc, however in general (excluding @Context) the
following types are supported:

1. Types for which a ParamConverter is available via
   a registered ParamConverterProvider. See Javadoc for these classes for
   more information.
2. Primitive types.
3. Types that have a constructor that accepts a single
   String argument.
4. Types that have a static method named valueOf or
   fromString with a single String argument that return an instance of
   the type. If both methods are present then valueOf MUST be used unless
   the type is an enum in which case fromString MUST be usedfootnote:[Due
   to limitations of the built-in valueOf method that is part of all Java
   enumerations, a fromString method is often defined by the enum
   writers. Consequently, the fromString method is preferred when
   available.].
5. List<T>, Set<T>, or SortedSet<T>, where T satisfies
   1,3 or 4 above.

It seems like we should support array types in places where we support List types (e.g. @CookieParam, @FormParam, @HeaderParam, @MatrixParam, and @QueryParam - @BeanParam and @PathParam do not support Lists, so should not support arrays either).

The MicroProfile Metrics community incorrectly assumed that arrays were already supported (see conversation here: https://groups.google.com/forum/#!topic/microprofile/yxoelXvk3o8 ).

Arrays already seem to be supported in Apache CXF and RESTEasy. I have not tested Jersey, but I assume that they are not supported based on the MP Metrics conversation.

If nobody objects, I can open a PR to update the spec text and Javadoc. Since this changes behavior, it would need to be released post-EE9.

[mkarg]

Sounds reasonable. Thank your for bringing this forward.