@Override
	public boolean isStale(SimpleModuleDefinition targetDefinition, SimpleModuleDefinition sourceDefinition) {
		if (targetDefinition == null) {
			return true;
		}

		String md5SourceLocation = sourceDefinition.getLocation() + ".md5";
		String md5TargetLocation = targetDefinition.getLocation() + ".md5";

		String md5Source = readHash(md5SourceLocation);
		String md5Target = readHash(md5TargetLocation);

		return md5Target == null || md5Source == null || !md5Source.equals(md5Target);
	}
A {@link org.springframework.xd.dirt.module.StalenessCheck} that expects to find a {@code .md5} file next to a
module archive and returns true if the computed hashes differ.

@see WritableResourceModuleRegistry
@since 1.2
@author Eric Bottard
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/module/MD5StalenessCheck.java