public CacheKey constructCacheKey() {
CompoundCacheKey cacheKey = new CompoundCacheKey();
try {
cacheKey.addCacheKey(new TimestampCacheKey(this.source, this.source.openConnection().getLastModified()));
cacheKey.addCacheKey(new ParameterCacheKey("contextParameters", this.parameters));
} catch (IOException e) {
throw new SetupException(e);
}
return cacheKey;