-Xpatch currently only supports exploded patches. There have been several requests to allow the patches be packaged as JAR files.

The proposal (not in JEP 261 yet) is that it change from a path to a stringified multi-map from module names to module-artifact paths

  Syntax: -Xpatch:<module>=<path>(,<module>=<path>)*
  Where:
    <module> is a module name
    <path> is the filesystem path name of a (partial) JAR file
           or exploded module
  Example: -Xpatch:java.base=/home/dl/jsr166.jar,java.corba=/opt/oracle/wlsorb.jar

  More than one mapping for a particular module can be specified
    The artifacts are searched, lazily, in the order they occur in the option
  A particular artifact can be used for more than one module
    Though that's likely to be confusing
  If a mapping is specified for a module that's never loaded,
     or an artifact that doesn't exist,
     -> Ignore it
  Artifacts used with -Xpatch must not contain module-info.class files
    A fatal error will be reported when this is detected (lazily)