@Override
	public boolean supports(Class<?> type, String optionContext) {
		return String.class.isAssignableFrom(type)
				&& (optionContext != null && optionContext.contains(EXISTING_PREFIX));
	}
Option Context of arguments that want to benefit from this converter should have this suffix present, with the
appended part representing the kind of entity they're interested in (<i>e.g.</i> {@code existing-stream}).
spring-xd-shell/src/main/java/org/springframework/xd/shell/converter/ExistingXDEntityConverter.java