Filing this for the record. There was a javac change starting around jdk6u4 that changed the way the source timestamps and zip file (or jar file) content time stamps impacted the build. We suspect it has something to do with places in the build where not all source files you want compiled are explicitly listed on the compile line. One occirance looks like:

/build/jdk/bootstrap/bin/java -XX:-PrintVMOptions -XX:+UnlockDiagnosticVMOptions -XX:-LogVMOutput -client -Xmx896m -Xms128m -XX:PermSize=32m -XX:MaxPermSize=160m -Xbootclasspath/p:/build/jdk/langtools/dist/bootstrap/lib/javac.jar -jar /build/jdk/langtools/dist/bootstrap/lib/javac.jar -source 7 -target 7 -encoding ascii -Xbootclasspath:/build/jdk/classes -sourcepath ../../../src/closed/solaris/classes:../../../src/closed/share/classes:/build/jdk/gensrc:../../../src/solaris/classes:../../../src/share/classes -d /build/jdk/classes @/build/jdk/tmp/java/java.lang.management/management/.classes.list.filtered
jdk/src/share/classes/sun/management/jmxremote/ConnectorBootstrap.java:661: cannot find symbol
                return new SslRMIServerSocketFactory(
                       ^
  symbol: constructor SslRMIServerSocketFactory(SSLContext,String[],String[],boolean)
  location: class SslRMIServerSocketFactory

...

This could be fixed by using -Xprefer:source, or not allowing implicit compilation (harder). Or setting a special properti in javac to fallback to the older sip access code.