title: GWT compile error: Rebind result cannot be abstract
body: <p>When i try to compile GWT i receive an error that com.allen_sauer.gwt.log.client.util.impl.DOMUtilImpl cannot be abstract. How to solve this error?</p>
  
  <p>I am using GWT 2.6.</p>
  
  <pre><code>Nov 24, 2014 3:29:42 PM java.util.prefs.WindowsPreferences &lt;init&gt;
  WARNING: Could not open/create prefs root node Software\JavaSoft\Prefs at root 0x80000002. Windows RegCreateKeyEx(...) returned error code 5.
  Compiling module nl.slimbetalen.slimbetalen
     Validating units:
        Ignored 5 units with compilation errors in first pass.
  Compile with -strict or with -logLevel set to TRACE or DEBUG to see all errors.
     [ERROR] Errors in 'com/allen_sauer/gwt/log/client/util/DOMUtil.java'
        [ERROR] Line 33: Rebind result 'com.allen_sauer.gwt.log.client.util.impl.DOMUtilImpl' cannot be abstract
  Exception in thread "pool-1-thread-1" java.lang.NullPointerException
      at com.google.gwt.dev.util.DiskCache.transferToStream(DiskCache.java:186)
      at com.google.gwt.dev.util.DiskCacheToken.writeObject(DiskCacheToken.java:73)
      at sun.reflect.GeneratedMethodAccessor30.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
      at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
      at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
      at java.io.ObjectOutputStream.writeObject0(Unknown Source)
      at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
      at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
      at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
      at java.io.ObjectOutputStream.writeObject0(Unknown Source)
      at java.io.ObjectOutputStream.writeObject(Unknown Source)
      at java.util.ArrayList.writeObject(Unknown Source)
      at sun.reflect.GeneratedMethodAccessor28.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
      at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
      at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
      at java.io.ObjectOutputStream.writeObject0(Unknown Source)
      at java.io.ObjectOutputStream.writeObject(Unknown Source)
      at com.google.gwt.dev.javac.CachedCompilationUnit.writeObject(CachedCompilationUnit.java:223)
      at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
      at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
      at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
      at java.io.ObjectOutputStream.writeObject0(Unknown Source)
      at java.io.ObjectOutputStream.writeObject(Unknown Source)
      at com.google.gwt.dev.javac.PersistentUnitCache$6.run(PersistentUnitCache.java:492)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
      at java.lang.Thread.run(Unknown Source)
  Exception in thread "pool-1-thread-3" java.lang.NullPointerException
      at com.google.gwt.dev.util.DiskCache.transferToStream(DiskCache.java:185)
      at com.google.gwt.dev.util.DiskCacheToken.writeObject(DiskCacheToken.java:73)
      at sun.reflect.GeneratedMethodAccessor30.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
      at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
      at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
      at java.io.ObjectOutputStream.writeObject0(Unknown Source)
      at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
      at java.io.ObjectOutputStream.defaultWriteObject(Unknown Source)
      at com.google.gwt.dev.javac.CachedCompilationUnit.writeObject(CachedCompilationUnit.java:222)
      at sun.reflect.GeneratedMethodAccessor32.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
      at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
      at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
      at java.io.ObjectOutputStream.writeObject0(Unknown Source)
      at java.io.ObjectOutputStream.writeObject(Unknown Source)
      at com.google.gwt.dev.javac.PersistentUnitCache$6.run(PersistentUnitCache.java:492)
      at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
      at java.lang.Thread.run(Unknown Source)
  </code></pre>