The following style updates have been made in anticipation of
substantive changes in subsequent commits:

 - organize imports
 - correct whitespace errors (leading spaces in code, tabs in Javadoc)
 - wrap Javadoc at 90 chars; make imperative ("Return" vs. "Returns")
 - use conventional constructor argument wrapping

A serialVersionUID has also been added to RestClientException and its
ResourceAccessException subclass for consistency with the rest of that
same exception hierarchy.

Issue: SPR-7938