public GradleHandle start() {
if (execHandle != null) {
throw new IllegalStateException("you have already called start() on this handle");
}
AbstractExecHandleBuilder execBuilder = execHandleFactory.create();
execBuilder.setStandardOutput(new CloseShieldOutputStream(new TeeOutputStream(System.out, standardOutput)));
execBuilder.setErrorOutput(new CloseShieldOutputStream(new TeeOutputStream(System.err, errorOutput)));
execHandle = execBuilder.build();
execHandle.start();
return this;
}