When compiling something with javac and using multiple -Xpatch arguments to patch multiple modules in the JDK, e.g., for testing, javac seems to be ignoring all but the last -Xpatch argument.

For example:
javac \
    -Xpatch:jdk.foo=/path/to/jdk.foo \
    -Xpatch:jdk.bar=/path/to/jdk.bar \
    /path/to/SomeClass.java

If SomeClass.java relies on any classes that may be patched into jdk.foo by the -Xpatch arg above then it will fail to compile.

If I reverse the args so jdk.foo is last (and assuming there are no dependencies on jdk.bar), or eliminate jdk.bar entirely then SomeClass will compile.

Once it's compiled, the java launcher seems to work just fine with multiple -Xpatch arguments, regardless of argument order:
java \
    -Xpatch:jdk.foo=/path/to/jdk.foo \
    -Xpatch:jdk.bar=/path/to/jdk.bar \
    -cp /path/to
    SomeClass