Dev sources. Unsafe synchronization on this in both getResources and
propertyChange conflicts with ProjectManager.mutex.

"Java Source Worker Thread" prio=1 tid=0x08bd5a40 nid=0x5efe in Object.wait()
[0x974ce000..0x974cf130]
        at java.lang.Object.wait(Native Method)
        - waiting on <0xa2e47730> (a org.openide.util.Mutex$QueueCell)
        at java.lang.Object.wait(Object.java:474)
        at org.openide.util.Mutex$QueueCell.sleep(Mutex.java:1447)
        - locked <0xa2e47730> (a org.openide.util.Mutex$QueueCell)
        at org.openide.util.Mutex.enterImpl(Mutex.java:631)
        at org.openide.util.Mutex.enter(Mutex.java:538)
        at org.openide.util.Mutex.readEnter(Mutex.java:521)
        at org.openide.util.Mutex.readAccess(Mutex.java:227)
        at
org.netbeans.spi.project.support.ant.PropertyUtils$SequentialPropertyEvaluator.getProperty(PropertyUtils.java:786)
        at
org.netbeans.modules.web.project.classpath.SourcePathImplementation.getResources(SourcePathImplementation.java:88)
        - locked <0xa212ef18> (a
org.netbeans.modules.web.project.classpath.SourcePathImplementation)
        at org.netbeans.api.java.classpath.ClassPath.entries(ClassPath.java:251)
[...]


"Default RequestProcessor" daemon prio=1 tid=0x086d2e60 nid=0x5ef5 waiting for
monitor entry [0x97dd5000..0x97dd5db0]
        at
org.netbeans.modules.web.project.classpath.SourcePathImplementation.propertyChange(SourcePathImplementation.java:137)
        - waiting to lock <0xa212ef18> (a
org.netbeans.modules.web.project.classpath.SourcePathImplementation)
        at
java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:333)
        at
java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:270)
        at
org.netbeans.modules.web.project.SourceRoots.resetCache(SourceRoots.java:372)
        at
org.netbeans.modules.web.project.SourceRoots.access$1100(SourceRoots.java:62)
        at
org.netbeans.modules.web.project.SourceRoots$ProjectMetadataListener.configurationXmlChanged(SourceRoots.java:405)
        at sun.reflect.GeneratedMethodAccessor41.invoke(Unknown Source)
        at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at
org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:424)
        at $Proxy6.configurationXmlChanged(Unknown Source)
        at
org.netbeans.spi.project.support.ant.AntProjectHelper$6.run(AntProjectHelper.java:468)
        at
org.netbeans.spi.project.support.ant.AntProjectHelper$6.run(AntProjectHelper.java:464)
        at org.openide.util.Mutex.readAccess(Mutex.java:230)
        at
org.netbeans.spi.project.support.ant.AntProjectHelper.fireChange(AntProjectHelper.java:463)
[...]


Detected while trying to verify fix of issue #92287.