Widgetset can't compile. Vaadin 7.5.1. Eclipse plugin.

java.lang.NoClassDefFoundError: org/objectweb/asm/ClassVisitor
at com.google.gwt.dev.javac.CompiledClass.getSignatureHash(CompiledClass.java:166)
at com.google.gwt.dev.javac.Dependencies$Ref.(Dependencies.java:42)
at com.google.gwt.dev.javac.Dependencies$Ref.(Dependencies.java:37)
at com.google.gwt.dev.javac.Dependencies.resolve(Dependencies.java:114)
at com.google.gwt.dev.javac.CompilationStateBuilder$CompileMoreLater.compile(CompilationStateBuilder.java:366)
at com.google.gwt.dev.javac.CompilationStateBuilder.doBuildFrom(CompilationStateBuilder.java:580)
at com.google.gwt.dev.javac.CompilationStateBuilder.buildFrom(CompilationStateBuilder.java:513)
at com.google.gwt.dev.javac.CompilationStateBuilder.buildFrom(CompilationStateBuilder.java:499)
at com.google.gwt.dev.cfg.ModuleDef.getCompilationState(ModuleDef.java:668)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:255)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:229)
at com.google.gwt.dev.Precompile.precompile(Precompile.java:145)
at com.google.gwt.dev.Compiler.run(Compiler.java:206)
at com.google.gwt.dev.Compiler.run(Compiler.java:158)
at com.google.gwt.dev.Compiler$1.run(Compiler.java:120)
at com.google.gwt.dev.CompileTaskRunner.doRun(CompileTaskRunner.java:55)
at com.google.gwt.dev.CompileTaskRunner.runWithAppropriateLogger(CompileTaskRunner.java:50)
at com.google.gwt.dev.Compiler.main(Compiler.java:127)
at com.vaadin.tools.WidgetsetCompiler$1.run(WidgetsetCompiler.java:80)
at java.lang.Thread.run(Thread.java:744)