Groovy JsonBuilder throws NoClassDefFoundError when using camel-groovy component

Issue

Getting NoClassDefFoundError While working with JsonBuilder.toString() in Groovy code inside a Camel route, which runs inside Jboss Fuse 7 running on top of EAP 7.

The code looks like so:

def builder = new JsonBuilder()
builder {
'myField': myFieldVal
}
return builder.toString()

The builder.toString() method invocation produces the following error:

Caused by: java.lang.NoClassDefFoundError: Could not initialize class 
groovy.json.internal.FastStringUtils