Hi there,
I'm trying to convert some of the projects to Gradle and during this process I'm getting NullPointerException on all existing Eclipse projects. It happens with both, Juno and Indigo releases.

Code:
!ENTRY org.springsource.ide.eclipse.gradle.core 4 0 2013-01-07 19:23:07.374
!MESSAGE 
!STACK 0
java.lang.NullPointerException
        at org.springsource.ide.eclipse.gradle.core.util.NatureUtils.ensure(NatureUtils.java:32)
        at org.springsource.ide.eclipse.gradle.core.GradleProject.convertToGradleProject(GradleProject.java:659)
        at org.springsource.ide.eclipse.gradle.ui.actions.ConvertToGradleProjectActionDelegate$1.doit(ConvertToGradleProjectActionDelegate.java:54)
        at org.springsource.ide.eclipse.gradle.core.util.GradleRunnable$1.run(GradleRunnable.java:50)
        at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
I did verify that metadata contains required Java nature.

Code:
<?xml version="1.0" encoding="UTF-8"?>
<projectDescription>
        <name>util</name>
        <comment></comment>
        <projects>
        </projects>
        <buildSpec>
                <buildCommand>
                        <name>org.eclipse.jdt.core.javabuilder</name>
                        <arguments>
                        </arguments>
                </buildCommand>
                <buildCommand>
                        <name>edu.umd.cs.findbugs.plugin.eclipse.findbugsBuilder</name>
                        <arguments>
                        </arguments>
                </buildCommand>
        </buildSpec>
        <natures>
                <nature>org.eclipse.jdt.core.javanature</nature>
                <nature>edu.umd.cs.findbugs.plugin.eclipse.findbugsNature</nature>
        </natures>
</projectDescription>
Even in cases when I don't have FindBugs nature, I'm still getting NullPointerException. The interesting thing is that I'm able to convert any newly Java projects into Gradle type of projects. After careful comparison I cannot find material difference between new and existing projects though.

Any ideas?