The reason seems to be that the classpath does not contain Apache Ivy and probably other dependencies.
Here is the error displayed when using Grab:
[92t0@trydev.activeeon.com;11:16:11] Failed to execute task: org/apache/ivy/core/report/ResolveReport
[92t0@trydev.activeeon.com;11:16:11] java.lang.NoClassDefFoundError: org/apache/ivy/core/report/ResolveReport
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.getDeclaredMethods0(Native Method)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.privateGetPublicMethods(Class.java:2902)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.getMethods(Class.java:1615)
[92t0@trydev.activeeon.com;11:16:11] at java.beans.Introspector.getPublicDeclaredMethods(Introspector.java:1336)
[92t0@trydev.activeeon.com;11:16:11] at java.beans.Introspector.getTargetMethodInfo(Introspector.java:1197)
[92t0@trydev.activeeon.com;11:16:11] at java.beans.Introspector.getBeanInfo(Introspector.java:426)
[92t0@trydev.activeeon.com;11:16:11] at java.beans.Introspector.getBeanInfo(Introspector.java:173)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.MetaClassImpl$15.run(MetaClassImpl.java:3292)
[92t0@trydev.activeeon.com;11:16:11] at java.security.AccessController.doPrivileged(Native Method)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.MetaClassImpl.addProperties(MetaClassImpl.java:3290)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.MetaClassImpl.initialize(MetaClassImpl.java:3266)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.reflection.ClassInfo.getMetaClassUnderLock(ClassInfo.java:254)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.reflection.ClassInfo.getMetaClass(ClassInfo.java:285)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.GrapeIvy.$getStaticMetaClass(GrapeIvy.groovy)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.GrapeIvy.<init>(GrapeIvy.groovy:81)
[92t0@trydev.activeeon.com;11:16:11] at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
[92t0@trydev.activeeon.com;11:16:11] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
[92t0@trydev.activeeon.com;11:16:11] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.newInstance(Class.java:442)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.Grape.getInstance(Grape.java:121)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.Grape.grab(Grape.java:159)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.GrabAnnotationTransformation.visit(GrabAnnotationTransformation.java:378)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.transform.ASTTransformationVisitor$3.call(ASTTransformationVisitor.java:321)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.control.CompilationUnit.applyToSourceUnits(CompilationUnit.java:931)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:593)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:569)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:546)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.GroovyClassLoader.doParseClass(GroovyClassLoader.java:298)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:268)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:254)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:212)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.getScriptClass(GroovyScriptEngineImpl.java:374)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.eval(GroovyScriptEngineImpl.java:151)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.eval(GroovyScriptEngineImpl.java:130)
[92t0@trydev.activeeon.com;11:16:11] at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:249)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scripting.Script.execute(Script.java:319)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scripting.ScriptHandler.handle(ScriptHandler.java:76)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.InProcessTaskExecutor.execute(InProcessTaskExecutor.java:198)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.InProcessTaskExecutor.execute(InProcessTaskExecutor.java:141)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.forked.env.ExecuteForkedTaskInsideNewJvm.fromForkedJVM(ExecuteForkedTaskInsideNewJvm.java:88)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.forked.env.ExecuteForkedTaskInsideNewJvm.main(ExecuteForkedTaskInsideNewJvm.java:78)
[92t0@trydev.activeeon.com;11:16:11] Caused by: java.lang.ClassNotFoundException: org.apache.ivy.core.report.ResolveReport
[92t0@trydev.activeeon.com;11:16:11] at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
[92t0@trydev.activeeon.com;11:16:11] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
[92t0@trydev.activeeon.com;11:16:11] ... 43 more
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.InProcessTaskExecutor.execute(InProcessTaskExecutor.java:202)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.InProcessTaskExecutor.execute(InProcessTaskExecutor.java:141)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.forked.env.ExecuteForkedTaskInsideNewJvm.fromForkedJVM(ExecuteForkedTaskInsideNewJvm.java:88)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.forked.env.ExecuteForkedTaskInsideNewJvm.main(ExecuteForkedTaskInsideNewJvm.java:78)
[92t0@trydev.activeeon.com;11:16:11] Caused by: java.lang.Exception: org/apache/ivy/core/report/ResolveReport
[92t0@trydev.activeeon.com;11:16:11] java.lang.NoClassDefFoundError: org/apache/ivy/core/report/ResolveReport
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.getDeclaredMethods0(Native Method)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.privateGetPublicMethods(Class.java:2902)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.getMethods(Class.java:1615)
[92t0@trydev.activeeon.com;11:16:11] at java.beans.Introspector.getPublicDeclaredMethods(Introspector.java:1336)
[92t0@trydev.activeeon.com;11:16:11] at java.beans.Introspector.getTargetMethodInfo(Introspector.java:1197)
[92t0@trydev.activeeon.com;11:16:11] at java.beans.Introspector.getBeanInfo(Introspector.java:426)
[92t0@trydev.activeeon.com;11:16:11] at java.beans.Introspector.getBeanInfo(Introspector.java:173)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.MetaClassImpl$15.run(MetaClassImpl.java:3292)
[92t0@trydev.activeeon.com;11:16:11] at java.security.AccessController.doPrivileged(Native Method)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.MetaClassImpl.addProperties(MetaClassImpl.java:3290)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.MetaClassImpl.initialize(MetaClassImpl.java:3266)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.reflection.ClassInfo.getMetaClassUnderLock(ClassInfo.java:254)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.reflection.ClassInfo.getMetaClass(ClassInfo.java:285)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.GrapeIvy.$getStaticMetaClass(GrapeIvy.groovy)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.GrapeIvy.<init>(GrapeIvy.groovy:81)
[92t0@trydev.activeeon.com;11:16:11] at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
[92t0@trydev.activeeon.com;11:16:11] at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
[92t0@trydev.activeeon.com;11:16:11] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.reflect.Constructor.newInstance(Constructor.java:422)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.Class.newInstance(Class.java:442)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.Grape.getInstance(Grape.java:121)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.Grape.grab(Grape.java:159)
[92t0@trydev.activeeon.com;11:16:11] at groovy.grape.GrabAnnotationTransformation.visit(GrabAnnotationTransformation.java:378)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.transform.ASTTransformationVisitor$3.call(ASTTransformationVisitor.java:321)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.control.CompilationUnit.applyToSourceUnits(CompilationUnit.java:931)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:593)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:569)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:546)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.GroovyClassLoader.doParseClass(GroovyClassLoader.java:298)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:268)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:254)
[92t0@trydev.activeeon.com;11:16:11] at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:212)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.getScriptClass(GroovyScriptEngineImpl.java:374)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.eval(GroovyScriptEngineImpl.java:151)
[92t0@trydev.activeeon.com;11:16:11] at org.codehaus.groovy.jsr223.GroovyScriptEngineImpl.eval(GroovyScriptEngineImpl.java:130)
[92t0@trydev.activeeon.com;11:16:11] at javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:249)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scripting.Script.execute(Script.java:319)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scripting.ScriptHandler.handle(ScriptHandler.java:76)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.InProcessTaskExecutor.execute(InProcessTaskExecutor.java:198)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.InProcessTaskExecutor.execute(InProcessTaskExecutor.java:141)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.forked.env.ExecuteForkedTaskInsideNewJvm.fromForkedJVM(ExecuteForkedTaskInsideNewJvm.java:88)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.forked.env.ExecuteForkedTaskInsideNewJvm.main(ExecuteForkedTaskInsideNewJvm.java:78)
[92t0@trydev.activeeon.com;11:16:11] Caused by: java.lang.ClassNotFoundException: org.apache.ivy.core.report.ResolveReport
[92t0@trydev.activeeon.com;11:16:11] at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
[92t0@trydev.activeeon.com;11:16:11] at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
[92t0@trydev.activeeon.com;11:16:11] at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
[92t0@trydev.activeeon.com;11:16:11] ... 43 more
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scripting.Script.execute(Script.java:339)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scripting.ScriptHandler.handle(ScriptHandler.java:76)
[92t0@trydev.activeeon.com;11:16:11] at org.ow2.proactive.scheduler.task.executors.InProcessTaskExecutor.execute(InProcessTaskExecutor.java:198)
[92t0@trydev.activeeon.com;11:16:11] ... 3 more
Currently it is not possible to use the @Grab annotation in groovy scripts executed in a task.
@Grab is a very handy tool allowing to download dynamically from maven dependencies used inside a script.
http://docs.groovy-lang.org/latest/html/documentation/grape.html
The reason seems to be that the classpath does not contain Apache Ivy and probably other dependencies.
Here is the error displayed when using Grab: