@Override
	public void validateBeforeDeploy(String name, Map<String, String> properties) {
		Assert.hasText(name, "name cannot be blank or null");
		Assert.notNull(properties, "properties cannot be null");
		D definition = getDefinitionRepository().findOne(name);
		if (definition == null) {
			throwNoSuchDefinitionException(name);
		}
		if (instanceRepository.exists(name)) {
			throwAlreadyDeployedException(name);
		}
	}
Un-deploy the deployment unit with the given name

@param deploymentUnitName the deployment unit name
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/stream/AbstractInstancePersistingDeployer.java