code: public static Throwable deepSanitize(Throwable t) {
          Throwable current = t;
          while (current.getCause() != null) {
              current = StackTraceUtils.sanitize(current.getCause());
          }
          return StackTraceUtils.sanitize(t);
      }
docs: Sanitize the exception and ALL nested causes
  <p>
  This will MODIFY the stacktrace of the exception instance and all its causes irreversibly
  
  @param t a throwable
  @return The root cause exception instances, with stack trace modified to filter out groovy runtime classes