Merge pull request #2535 from FarmGeek4Life/master

Update the FAQ for using a custom cache implementation

Docs/faq/CustomCache.md

@@ -6,6 +6,42 @@ implementation, see the Javadoc of `waffle.util.cache.Cache#newCache`…also sho
 
 ```javadoc
     * The cache implementation is obtained using {@link ServiceLoader}. To create your own implementation, implement
-    * {@link CacheSupplier} and register it using the {@code /META-INF/services/waffle.cache.CacheSupplier} file on
-    * your classpath.
+    * {@link CacheSupplier} and register it using the {@code /META-INF/services/waffle.util.cache.CacheSupplier} file
+    * on your classpath.
+```
+
+### Error message (in log file)
+`No CacheSupplier implementation found by ServiceLoader. Please see 
+https://github.com/Waffle/waffle/blob/master/Docs/faq/CustomCache.md for possible solutions. Falling back to default
+CaffeineCache implementation.`
+
+#### Solutions
+See the primary answer above for specifying a custom cache, or even just re-specifying the default load of 
+`waffle.util.cache.CaffeineCacheSupplier`, by using the `META-INF/services/waffle.util.cache.CacheSupplier` file on
+your classpath.
+
+If you are still getting the message after trying that (most likely in use cases where you don't have much control
+over the application classpath, like in a plugin environment), then you may need to adapt the thread
+ContextClassLoader prior to the call in your code that leads to the error message, like in the below example. Note
+that this is a workaround for when providing the file mentioned above in your classpath just doesn't work.
+
+```java
+// Save the current ContextClassLoader
+Thread thread = Thread.currentThread();
+ClassLoader loader = thread.getContextClassLoader();
+
+// Set the desired ContextClassLoader
+// In this case, using CacheSupplier to use the default CacheSupplier specified by the waffle-jna package
+// You may choose a different class in the waffle-jna package
+// You will want to choose a class in your classpath if you use the 
+//   META-INF/services/waffle.util.cache.CacheSupplier file to provide a custom cache implementation
+thread.setContextClassLoader(CacheSupplier.class.getClassLoader());
+
+// Call Waffle-jna code that produced the error
+// example:
+try {
+    this.negotiateSecurityFilter.init();
+} finally {
+    thread.setContextClassLoader(loader);
+}
 ```