@Override
    public int hashCode() {
        return key.hashCode() + 37 * defMd5.hashCode();
    }
Constructs new key

@param name           config definition name
@param configIdString Can be null.
@param namespace      namespace for this config definition
@param defMd5         MD5 checksum of the config definition. Never null.
config/src/main/java/com/yahoo/vespa/config/ConfigCacheKey.java