private boolean supportsType(Class<?> clazz, Class<?>[] supportedTypes) {
		if (supportedTypes != null) {
			for (Class<?> targetType : supportedTypes) {
				if (ClassUtils.isAssignable(clazz, targetType)) {
					return true;
				}
			}
			return false;
		}
		return true;
	}
Subclasses implement this to specify supported payload types

@return an array of supported classes or null if any target type is supported
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/integration/bus/converter/AbstractFromMessageConverter.java