Since JDK 6+ on OS X there’s no classes.jar anymore! It’s content is
now part of rt.jar. As an example on my Sony-VAIO laptop running
Mavericks 10.9.1 on it, I’ve got it here:

/Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk/Contents/Home/jre/lib/
rt.jar

Note that the default-profile is fine for OS-X as well. E.g. I’ve got
JAVA_HOME as:

~>mvn -v
Apache Maven 3.0.5 (r01de14724cdef164cd33c7c8c2fe155faf9602da;
2013-02-19 14:51:28+0100)
Maven home: /Users/bvahdat/dev/apache-maven-3.0.5
Java version: 1.7.0_45, vendor: Oracle Corporation
Java home:
/Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.9.1", arch: "x86_64", family: "mac"

And tools.jar is under the path:

/Library/Java/JavaVirtualMachines/jdk1.7.0_45.jdk/Contents/Home/jre/../l
ib/tools.jar

So it’s all fine with the default-profile even on OS-X :)

Otherwise as expected, you get the following warning while jetty boots
up:

WARN  | Scanner-0 | Local JVM discovery disabled as this JVM cannot
access com.sun.tools.attach.VirtualMachine due to:
java.lang.NoClassDefFoundError: com/sun/tools/attach/VirtualMachine