@Override
	public boolean supports(Class<?> type, String optionContext) {
		String[] options = optionContext.split(" ");
		for (String option : options) {
			if (option.startsWith(COMPLETION_CONTEXT_PREFIX)) {
				return type == String.class;
			}
		}
		return false;
	}
To appear in the optionContext. Triggers the use of this converter and specifies which kind of completion is
expected.
spring-xd-shell/src/main/java/org/springframework/xd/shell/converter/CompletionConverter.java