private String separate(Object... strings) {
        requireNonNullElements(strings);
        
		return Stream.of(strings)
			.map(Object::toString)
			.filter(s -> s.length() > 0)
			.collect(joining(dnl()));
	}
Converts the specified elements into strings using their
<code>toString</code>-method and combines them with two new-line-characters.
Empty strings will be discarded.

@param strings  the strings to combine
@return         the combined string
common-parent/codegen/src/main/java/com/speedment/common/codegen/internal/java/view/ClassOrInterfaceView.java