GroovyEclipseBug: "Cannot find type variable on method" (private static method in Java class)

I get the GroovyEclipseBug shown below.

The method:
private static T getMandatoryVal(Map map, String key, Class clazz)
is delcared in a Java class SshjTool. The method is only called from within this class.

The comilation error is reported on a different groovy class: EffectorSayHiTest.groovy, at line 0.

—
General error during class generation: Cannot find type variable on method declaring element private static T getMandatoryVal(Map, java.lang.String, Class)

org.codehaus.jdt.groovy.internal.compiler.ast.GroovyEclipseBug: Cannot find type variable on method declaring element private static T getMandatoryVal(Map, java.lang.String, Class)
at org.codehaus.jdt.groovy.internal.compiler.ast.JDTResolver.createClassNode(JDTResolver.java:531)
at org.codehaus.jdt.groovy.internal.compiler.ast.JDTResolver.createJDTClassNode(JDTResolver.java:448)
at org.codehaus.jdt.groovy.internal.compiler.ast.JDTResolver.convertToClassNode(JDTResolver.java:436)
at org.codehaus.jdt.groovy.internal.compiler.ast.JDTClassNode.methodBindingToMethodNode(JDTClassNode.java:336)
at org.codehaus.jdt.groovy.internal.compiler.ast.JDTClassNode.initializeMembers(JDTClassNode.java:298)
at org.codehaus.jdt.groovy.internal.compiler.ast.JDTClassNode.initialize(JDTClassNode.java:231)
at org.codehaus.jdt.groovy.internal.compiler.ast.JDTClassNode.lazyClassInit(JDTClassNode.java:155)
at org.codehaus.groovy.ast.ClassNode.getInterfaces(ClassNode.java:444)
at org.codehaus.groovy.ast.ClassNode.declaresInterface(ClassNode.java:1051)
at org.codehaus.groovy.ast.ClassNode.implementsInterface(ClassNode.java:1031)
at org.codehaus.groovy.ast.ClassNode.isDerivedFromGroovyObject(ClassNode.java:1021)
at org.codehaus.groovy.classgen.AsmClassGenerator.loadWrapper(AsmClassGenerator.java:1509)
at org.codehaus.groovy.classgen.asm.CallSiteWriter.makeCallSite(CallSiteWriter.java:303)
at org.codehaus.groovy.classgen.asm.InvocationWriter.makeCall(InvocationWriter.java:187)
at org.codehaus.groovy.classgen.asm.InvocationWriter.makeCall(InvocationWriter.java:89)
at org.codehaus.groovy.classgen.asm.InvocationWriter.makeInvokeMethodCall(InvocationWriter.java:73)
at org.codehaus.groovy.classgen.asm.InvocationWriter.writeInvokeMethod(InvocationWriter.java:292)
at org.codehaus.groovy.classgen.AsmClassGenerator.visitMethodCallExpression(AsmClassGenerator.java:657)
at org.codehaus.groovy.ast.expr.MethodCallExpression.visit(MethodCallExpression.java:75)
at org.codehaus.groovy.classgen.asm.StatementWriter.writeReturn(StatementWriter.java:579)
at org.codehaus.groovy.classgen.asm.OptimizingStatementWriter.writeReturn(OptimizingStatementWriter.java:316)
at org.codehaus.groovy.classgen.AsmClassGenerator.visitReturnStatement(AsmClassGenerator.java:499)
at org.codehaus.groovy.ast.stmt.ReturnStatement.visit(ReturnStatement.java:47)
at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitClassCodeContainer(ClassCodeVisitorSupport.java:102)
at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitConstructorOrMethod(ClassCodeVisitorSupport.java:113)
at org.codehaus.groovy.classgen.AsmClassGenerator.visitStdMethod(AsmClassGenerator.java:313)
at org.codehaus.groovy.classgen.AsmClassGenerator.visitConstructorOrMethod(AsmClassGenerator.java:270)
at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitMethod(ClassCodeVisitorSupport.java:124)
at org.codehaus.groovy.classgen.AsmClassGenerator.visitMethod(AsmClassGenerator.java:390)
at org.codehaus.groovy.ast.ClassNode.visitContents(ClassNode.java:1170)
at org.codehaus.groovy.ast.ClassCodeVisitorSupport.visitClass(ClassCodeVisitorSupport.java:51)
at org.codehaus.groovy.classgen.AsmClassGenerator.visitClass(AsmClassGenerator.java:174)
at org.codehaus.groovy.control.CompilationUnit$6.call(CompilationUnit.java:829)
at org.codehaus.groovy.control.CompilationUnit.applyToPrimaryClassNodes(CompilationUnit.java:1122)
at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:594)
at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:572)
at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:549)
at org.codehaus.jdt.groovy.internal.compiler.ast.GroovyCompilationUnitDeclaration.processToPhase(GroovyCompilationUnitDeclaration.java:171)
at org.codehaus.jdt.groovy.internal.compiler.ast.GroovyCompilationUnitDeclaration.generateCode(GroovyCompilationUnitDeclaration.java:1526)
at org.eclipse.jdt.internal.compiler.Compiler.process(Compiler.java:831)
at org.eclipse.jdt.internal.compiler.ProcessTaskManager.run(ProcessTaskManager.java:137)
at java.lang.Thread.run(Thread.java:680)

—
This is with org.codehause.groovy.eclipse version 2.6.0, in Eclipse Indigo Service Release 2.

—
See https://github.com/brooklyncentral/brooklyn/issues/50.

You should be able to see the error by building the brooklyn repo with, for example, git commit b302e7.