GWT SpringRoo: Exception thrown while constructing Processor object

I am building a simple SpringRoo + GWT app to be deploy to GAE. I'm just at the initial stage of development. I have a simple index.jspx page generated using SpringRoo to be handled by a SpringMVC controller (also generated by SpringRoo). I encountered this error: Exception thrown while constructing Processor object: org/datanucleus/exceptions/NucleusException after I ran mvn gwt:run. The error occurred as a compilation error.

So I ran mvn -X gwt:run to debug the code execution. The output shows:

[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] error: Exception thrown while constructing Processor object: org/datanuc
leus/exceptions/NucleusException
[INFO] 1error
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 3:17.328s
[INFO] Finished at: Fri Feb 11 13:44:59 GMT 2011
[INFO] Final Memory: 12M/23M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.
1:compile (default-compile) on project opevel: Compilation failure
[ERROR] error: Exception thrown while constructing Processor object: org/datanuc
leus/exceptions/NucleusException
[ERROR] -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal o
rg.apache.maven.plugins:maven-compiler-plugin:2.1:compile (default-compile) on p
roject: Compilation failure
error: Exception thrown while constructing Processor object: org/datanucleus/exc
eptions/NucleusException

        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor
.java:213)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor
.java:153)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor
.java:145)
        at org.apache.maven.lifecycle.internal.MojoExecutor.executeForkedExecuti
ons(MojoExecutor.java:365)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor
.java:199)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor
.java:153)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor
.java:145)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProje
ct(LifecycleModuleBuilder.java:84)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProje
ct(LifecycleModuleBuilder.java:59)
        at org.apache.maven.lifecycl开发者_如何学JAVAe.internal.LifecycleStarter.singleThreadedBu
ild(LifecycleStarter.java:183)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(Lifecycl
eStarter.java:161)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:319)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:534)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Laun
cher.java:290)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.jav
a:230)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(La
uncher.java:409)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:
352)
Caused by: org.apache.maven.plugin.CompilationFailureException: Compilation fail
ure
error: Exception thrown while constructing Processor object: org/datanucleus/exc
eptions/NucleusException

        at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompiler
Mojo.java:613)
        at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:116)
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(Default
BuildPluginManager.java:107)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor
.java:209)
        ... 23 more
[ERROR]
[ERROR]
[ERROR] For more information about the errors and possible solutions, please rea
d the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureExc
eption

I checked the help site and it says it has got to do with maven plugin. A bit googling points to maven datacleus plugin but there's not replication of this sort of error anywhere. I also saw a post having something to do with lack of GAE support for jspx. but i haven't deployed yet to gae. I just want to test the app in GWT dev mode.

Just to say, I'm still learning SpringRoo + GAE architecture. Will appreciate any help.

Regards

---

Check this one. It says it had the same problem and they suggest 2 fixes which you can try