GWTP - An error occured for ClassEnhancer "ASM" when trying to call the method "org.datanucleus.enhancer.asm.ASMClassEnhancer"

I am trying to setup GWTP in eclipse and create a simplest possible POC. I have installed Google plugin with GWT 2.6, Appengine 1.9.18 and GWTP plugin 0.6.1.
I am using Windows 7, and Eclipse luna 4.4
I have two java versions installed on my machine for different versions!!!
On terminal:
D:\project>echo %JAVA_HOME%
"D:\installations\java8"
D:\project>java -version
java version "1.8.0_40" Java(TM) SE Runtime Environment (build 1.8.0_40-b25) Java HotSpot(TM) 64-Bit Server VM (build 25.40-b25, mixed mode)
On Eclipse:
Under Window --> preferences --> Java --> InstalledJREs I have selected the appropriate Java 8 installation.
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I am trying to create the GWTP project like this :
enter image description here
As soon as I click, finish, I get the following error:
StackTrace:
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.resources.natures" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.resources.builders" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.resources.markers" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.resources.markers" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.resources.markers" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.resources.markers" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.ant.core.extraClasspathEntries" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.ant.core.antTasks" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.jdt.core.classpathContainerInitializer" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.team.core.fileTypes" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.runtime.applications" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.runtime.applications" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.contenttype.contentTypes" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.runtime.preferences" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
Mar 15, 2015 10:49:28 PM org.datanucleus.plugin.NonManagedPluginRegistry registerExtensions
WARNING: Extension Point "org.eclipse.core.runtime.preferences" not registered, but plugin "" defined in file:/D:/project/eclipse-jee-luna-R-win32-x86_64/eclipse/plugins/com.google.gwt.eclipse.sdkbundle_2.6.0/gwt-2.6.0/gwt-dev.jar refers to it.
DataNucleus Enhancer (version 1.1.4) : Enhancement of classes
Mar 15, 2015 10:49:28 PM org.datanucleus.enhancer.DataNucleusEnhancer addMessage
SEVERE: An error occured for ClassEnhancer "ASM" when trying to call the method "org.datanucleus.enhancer.asm.ASMClassEnhancer" on class "getClassNameForFileName" : null
java.lang.IllegalArgumentException
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.datanucleus.enhancer.asm.ASMClassEnhancer.getClassNameForFileName(ASMClassEnhancer.java:155)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getClassNameForFilename(DataNucleusEnhancer.java:920)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getFileMetadataForInput(DataNucleusEnhancer.java:736)
    at org.datanucleus.enhancer.DataNucleusEnhancer.enhance(DataNucleusEnhancer.java:545)
    at org.datanucleus.enhancer.DataNucleusEnhancer.main(DataNucleusEnhancer.java:1252)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.google.appengine.tools.enhancer.Enhancer.execute(Enhancer.java:74)
    at com.google.appengine.tools.enhancer.Enhance.<init>(Enhance.java:71)
    at com.google.appengine.tools.enhancer.Enhance.main(Enhance.java:51)
.
An error occured for ClassEnhancer "ASM" when trying to call the method "org.datanucleus.enhancer.asm.ASMClassEnhancer" on class "getClassNameForFileName" : null
java.lang.IllegalArgumentException
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.datanucleus.enhancer.asm.ASMClassEnhancer.getClassNameForFileName(ASMClassEnhancer.java:155)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getClassNameForFilename(DataNucleusEnhancer.java:920)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getFileMetadataForInput(DataNucleusEnhancer.java:736)
    at org.datanucleus.enhancer.DataNucleusEnhancer.enhance(DataNucleusEnhancer.java:545)
    at org.datanucleus.enhancer.DataNucleusEnhancer.main(DataNucleusEnhancer.java:1252)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.google.appengine.tools.enhancer.Enhancer.execute(Enhancer.java:74)
    at com.google.appengine.tools.enhancer.Enhance.<init>(Enhance.java:71)
    at com.google.appengine.tools.enhancer.Enhance.main(Enhance.java:51)
.
Mar 15, 2015 10:49:28 PM org.datanucleus.enhancer.DataNucleusEnhancer addMessage
SEVERE: An error occured for ClassEnhancer "ASM" when trying to call the method "org.datanucleus.enhancer.asm.ASMClassEnhancer" on class "getClassNameForFileName" : null
java.lang.IllegalArgumentException
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.datanucleus.enhancer.asm.ASMClassEnhancer.getClassNameForFileName(ASMClassEnhancer.java:155)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getClassNameForFilename(DataNucleusEnhancer.java:920)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getFileMetadataForInput(DataNucleusEnhancer.java:736)
    at org.datanucleus.enhancer.DataNucleusEnhancer.enhance(DataNucleusEnhancer.java:545)
    at org.datanucleus.enhancer.DataNucleusEnhancer.main(DataNucleusEnhancer.java:1252)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.google.appengine.tools.enhancer.Enhancer.execute(Enhancer.java:74)
    at com.google.appengine.tools.enhancer.Enhance.<init>(Enhance.java:71)
    at com.google.appengine.tools.enhancer.Enhance.main(Enhance.java:51)
.
An error occured for ClassEnhancer "ASM" when trying to call the method "org.datanucleus.enhancer.asm.ASMClassEnhancer" on class "getClassNameForFileName" : null
java.lang.IllegalArgumentException
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.datanucleus.enhancer.asm.ASMClassEnhancer.getClassNameForFileName(ASMClassEnhancer.java:155)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getClassNameForFilename(DataNucleusEnhancer.java:920)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getFileMetadataForInput(DataNucleusEnhancer.java:736)
    at org.datanucleus.enhancer.DataNucleusEnhancer.enhance(DataNucleusEnhancer.java:545)
    at org.datanucleus.enhancer.DataNucleusEnhancer.main(DataNucleusEnhancer.java:1252)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.google.appengine.tools.enhancer.Enhancer.execute(Enhancer.java:74)
    at com.google.appengine.tools.enhancer.Enhance.<init>(Enhance.java:71)
    at com.google.appengine.tools.enhancer.Enhance.main(Enhance.java:51)
.
.
An error occured for ClassEnhancer "ASM" when trying to call the method "org.datanucleus.enhancer.asm.ASMClassEnhancer" on class "getClassNameForFileName" : null
java.lang.IllegalArgumentException
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.datanucleus.enhancer.asm.ASMClassEnhancer.getClassNameForFileName(ASMClassEnhancer.java:155)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getClassNameForFilename(DataNucleusEnhancer.java:920)
    at org.datanucleus.enhancer.DataNucleusEnhancer.getFileMetadataForInput(DataNucleusEnhancer.java:736)
    at org.datanucleus.enhancer.DataNucleusEnhancer.enhance(DataNucleusEnhancer.java:545)
    at org.datanucleus.enhancer.DataNucleusEnhancer.main(DataNucleusEnhancer.java:1252)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.google.appengine.tools.enhancer.Enhancer.execute(Enhancer.java:74)
    at com.google.appengine.tools.enhancer.Enhance.<init>(Enhance.java:71)
    at com.google.appengine.tools.enhancer.Enhance.main(Enhance.java:51)
.
DataNucleus Enhancer completed with success for 0 classes. Timings : input=32 ms, enhance=0 ms, total=32 ms. Consult the log for full details
DataNucleus Enhancer completed and no classes were enhanced. Consult the log for full details
###EDIT###
After a clean reinstall, everything worked. A super detailed explanation of everything a GWTP beginner need to know can be tracked on this google group thred. https://groups.google.com/forum/#!topic/gwt-platform/5iE5B_RTCuQ
Solution
GWTP 0.6.1 is quite old. For eclipse Luna you need to install the newest version of the plugin. Install it from http://arcbees.github.io/gwtp-eclipse-plugin/