Remove no quota leased warning from quota handler inactive callback

When EPP SSL handshake is unsuccessful, #channelInactive is called but there are no quotas to return, because quotas are only leased upon the first #channelRead. There is no need to log a warning and throw an exception in this case because the handshake exception would have been thrown already. Throwing a second exception just crowds the log.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=197016756

java/google/registry/proxy/handler/QuotaHandler.java

@@ -150,15 +150,18 @@ public abstract class QuotaHandler extends ChannelInboundHandlerAdapter {
     }
 
     /**
-     * Returns the leased token back to the token store upon connection termination.
+     * Returns the leased token (if available) back to the token store upon connection termination.
      *
      * <p>A connection with concurrent quota needs to do this in order to maintain its quota number
      * invariance.
      */
     @Override
     public void channelInactive(ChannelHandlerContext ctx) {
-      checkNotNull(quotaResponse, "No quota was leased, return not possible.");
+      // If no reads occurred before the connection is inactive (for example when the handshake
+      // is not successful), no quota is leased and therefore no return is needed.
+      if (quotaResponse != null) {
         Future<?> unusedFuture = quotaManager.releaseQuota(QuotaRebate.create(quotaResponse));
+      }
       ctx.fireChannelInactive();
     }
   }