System.procTime triggers Error in AppEngine environment

[akbertram]

java.lang.NoClassDefFoundError: java.lang.management.ManagementFactory is a restricted class. Please see the Google App Engine developer's guide for more details.
at com.google.appengine.tools.development.agent.runtime.Runtime.reject(Runtime.java:51)
at org.renjin.primitives.System.procTime(System.java:331)
at org.renjin.primitives.R$primitive$proc$time.doApply(R$primitive$proc$time.java from WrapperSource:65)
at org.renjin.primitives.R$primitive$proc$time.apply(R$primitive$proc$time.java from WrapperSource:27)
at org.renjin.eval.Context.evaluateCall(Context.java:261)
at org.renjin.eval.Context.evaluate(Context.java:193)
at org.renjin.primitives.special.AssignLeftFunction.assignLeft(AssignLeftFunction.java:60)
at org.renjin.primitives.special.AssignLeftFunction.apply(AssignLeftFunction.java:44)
at org.renjin.eval.Context.evaluateCall(Context.java:261)
at org.renjin.eval.Context.evaluate(Context.java:193)
at org.renjin.primitives.special.BeginFunction.apply(BeginFunction.java:46)
at org.renjin.eval.Context.evaluateCall(Context.java:261)
at org.renjin.eval.Context.evaluate(Context.java:193)
at org.renjin.eval.Context.evaluate(Context.java:161)
at org.renjin.sexp.Closure.doApply(Closure.java:108)
at org.renjin.eval.ClosureDispatcher.apply(ClosureDispatcher.java:80)
at org.renjin.eval.ClosureDispatcher.applyClosure(ClosureDispatcher.java:65)
at org.renjin.sexp.Closure.apply(Closure.java:82)
at org.renjin.eval.Context.evaluateCall(Context.java:261)
at org.renjin.eval.Context.evaluate(Context.java:193)
at org.renjin.primitives.special.AssignLeftFunction.assignLeft(AssignLeftFunction.java:60)
at org.renjin.primitives.special.AssignLeftFunction.apply(AssignLeftFunction.java:44)
at org.renjin.eval.Context.evaluateCall(Context.java:261)
at org.renjin.eval.Context.evaluate(Context.java:193)
at org.renjin.primitives.special.BeginFunction.apply(BeginFunction.java:46)
at org.renjin.eval.Context.evaluateCall(Context.java:261)
at org.renjin.eval.Context.evaluate(Context.java:193)
at org.renjin.eval.Context.evaluate(Context.java:161)
at org.renjin.sexp.Closure.doApply(Closure.java:108)
at org.renjin.eval.ClosureDispatcher.apply(ClosureDispatcher.java:80)
at org.renjin.eval.ClosureDispatcher.applyClosure(ClosureDispatcher.java:65)
at org.renjin.sexp.Closure.apply(Closure.java:82)