private String dependencyKey(ModuleDefinition moduleDefinition) {
		return String.format("module:%s:%s", moduleDefinition.getType(), moduleDefinition.getName());
	}
Generates the key used in the ModuleDependencyRepository.

@param moduleDefinition the moduleDefinition being saved or deleted
@return generated key
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/module/store/ZooKeeperComposedModuleDefinitionRegistry.java