Add comment for large event rejection.

Author: phipag

powertools-logging/src/main/java/software/amazon/lambda/powertools/logging/internal/KeyBuffer.java

@@ -51,6 +51,7 @@ public KeyBuffer(int maxBytes, Function<T, Integer> sizeCalculator, Runnable ove
 
     public void add(K key, T event) {
         int eventSize = sizeCalculator.apply(event);
+        // Immediately reject events larger than the whole buffer-size to avoid evicting all elements.
         if (eventSize > maxBytes) {
             overflowTriggered.put(key, true);
             return;