code: public boolean contains(Class exType) {
  		if (exType == null) {
  			return false;
  		}
  		if (exType.isInstance(this)) {
  			return true;
  		}
  		Throwable cause = getCause();
  		if (cause == this) {
  			return false;
  		}
  		if (cause instanceof NestedCheckedException) {
  			return ((NestedCheckedException) cause).contains(exType);
  		}
  		else {
  			while (cause != null) {
  				if (exType.isInstance(cause)) {
  					return true;
  				}
  				if (cause.getCause() == cause) {
  					break;
  				}
  				cause = cause.getCause();
  			}
  			return false;
  		}
  	}
docs: Check whether this exception contains an exception of the given type:
  either it is of the given class itself or it contains a nested cause
  of the given type.
  @param exType the exception type to look for
  @return whether there is a nested exception of the specified type