FULL PRODUCT VERSION :
java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-b82)
Java HotSpot(TM) 64-Bit Server VM (build 1.9.0-ea-b82, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows 7 64-Bit

A DESCRIPTION OF THE PROBLEM :
This is an upstream bug report from JOSM for:
https://josm.openstreetmap.de/ticket/11577

We have found with early access builds of JDK9 an error when calling java.lang.management.ManagementFactory.getPlatformMBeanServer().

It sometimes results in a java.lang.NoClassDefFoundError: com/sun/management/internal/GarbageCollectorExtImpl

It is reproducible with build b68 and b82 on Windows 7. It seems to only occur on first invocation of the method. Further invocations do not have this error.

REGRESSION. Last worked in version 8u60

ADDITIONAL REGRESSION INFORMATION:
java version "1.8.0_60"
Java(TM) SE Runtime Environment (build 1.8.0_60-b27)
Java HotSpot(TM) 64-Bit Server VM (build 25.60-b23, mixed mode)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Call java.lang.management.ManagementFactory.getPlatformMBeanServer()

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
no error
ACTUAL -
java.lang.NoClassDefFoundError: com/sun/management/internal/GarbageCollectorExtImpl

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.lang.NoClassDefFoundError: com/sun/management/internal/GarbageCollectorExtImpl
at sun.management.MemoryImpl.getMemoryManagers0(Native Method)
at sun.management.MemoryImpl.getMemoryManagers(MemoryImpl.java:98)
at sun.management.ManagementFactoryHelper.getGarbageCollectorMXBeans(ManagementFactoryHelper.java:130)
at java.lang.management.DefaultPlatformMBeanProvider$4.nameToMBeanMap(DefaultPlatformMBeanProvider.java:185)
at java.lang.management.ManagementFactory.lambda$getPlatformMBeanServer$0(ManagementFactory.java:478)
at java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:269)
at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)
at java.util.HashMap$ValueSpliterator.forEachRemaining(HashMap.java:1664)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)
at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:430)
at java.lang.management.ManagementFactory.getPlatformMBeanServer(ManagementFactory.java:479)
at org.apache.commons.jcs.engine.control.CompositeCacheManager.initialize(CompositeCacheManager.java:262)
at org.apache.commons.jcs.engine.control.CompositeCacheManager.getUnconfiguredInstance(CompositeCacheManager.java:214)
at org.openstreetmap.josm.data.cache.JCSCacheManager.initialize(JCSCacheManager.java:117)

REPRODUCIBILITY :
This bug can be reproduced often.

---------- BEGIN SOURCE ----------
import java.lang.management.ManagementFactory;
import javax.management.MBeanServer;

MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
---------- END SOURCE ----------