[kafka] upgraded jmx keys for >= 0.8.2

[skip ci]
kafka updated their bean names.
See the documentation:
http://kafka.apache.org/082/documentation.html#monitoring
http://kafka.apache.org/081/documentation.html#monitoring

This won't work on older Kafka version so we added a warning
to link back to the old Kafka sample file if needed

[leo@datadoghq.com] Rebased on master and reindented
+ added warning

conf.d/kafka.yaml.example

@@ -1,18 +1,25 @@
+##########
+# WARNING
+##########
+# This sample works only for Kafka >= 0.8.2.
+# If you are running a version older than that, you can refer to agent 5.2.x released
+# sample files, https://raw.githubusercontent.com/DataDog/dd-agent/5.2.1/conf.d/kafka.yaml.example
+
 instances:
   - host: localhost
     port: 9999 # This is the JMX port on which Kafka exposes its metrics (usually 9999)
-  #   user: username
-  #   password: password
-  #   process_name_regex: .*process_name.* # Instead of specifying a host, and port. The agent can connect using the attach api.
-  #                                                                       #   This requires the JDK to be installed and the path to tools.jar to be set below.
-  #   tools_jar_path: /usr/lib/jvm/java-7-openjdk-amd64/lib/tools.jar # To be set when process_name_regex is set
-  #   name: kafka_instance
-  #   # java_bin_path: /path/to/java # Optional, should be set if the agent cannot find your java executable
-  #   # trust_store_path: /path/to/trustStore.jks # Optional, should be set if ssl is enabled
-  #   # trust_store_password: password
-  #   tags:
-  #     env: stage
-  #     newTag: test
+    # user: username
+    # password: password
+    # process_name_regex: .*process_name.* # Instead of specifying a host, and port. The agent can connect using the attach api.
+    #                                                                       #   This requires the JDK to be installed and the path to tools.jar to be set below.
+    # tools_jar_path: /usr/lib/jvm/java-7-openjdk-amd64/lib/tools.jar # To be set when process_name_regex is set
+    # name: kafka_instance
+    # java_bin_path: /path/to/java # Optional, should be set if the agent cannot find your java executable
+    # trust_store_path: /path/to/trustStore.jks # Optional, should be set if ssl is enabled
+    # trust_store_password: password
+    # tags:
+    #   env: stage
+    #   newTag: test
 
 init_config:
   is_jmx: true
@@ -23,47 +30,54 @@ init_config:
     # Aggregate cluster stats
     #
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="BrokerTopicMetrics",name="AllTopicsBytesOutPerSec"'
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=BrokerTopicMetrics,name=BytesOutPerSec'
         attribute:
           MeanRate:
             metric_type: gauge
-            alias: kafka.net.bytes_out
+          alias: kafka.net.bytes_out
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="BrokerTopicMetrics",name="AllTopicsBytesInPerSec"'
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=BrokerTopicMetrics,name=BytesInPerSec'
         attribute:
           MeanRate:
             metric_type: gauge
             alias: kafka.net.bytes_in
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="BrokerTopicMetrics",name="AllTopicsMessagesInPerSec"'
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=BrokerTopicMetrics,name=MessagesInPerSec'
         attribute:
           MeanRate:
             metric_type: gauge
             alias: kafka.messages_in
+    - include:
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=BrokerTopicMetrics,name=BytesRejectedPerSec'
+        attribute:
+          MeanRate:
+            metric_type: gauge
+            alias: kafka.net.bytes_rejected
 
     #
     # Request timings
     #
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="BrokerTopicMetrics",name="AllTopicsFailedFetchRequestsPerSec"'
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=BrokerTopicMetrics,name=FailedFetchRequestsPerSec'
         attribute:
           MeanRate:
             metric_type: gauge
             alias: kafka.request.fetch.failed
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="BrokerTopicMetrics",name="AllTopicsFailedProduceRequestsPerSec"'
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=BrokerTopicMetrics,name=FailedProduceRequestsPerSec'
         attribute:
           MeanRate:
             metric_type: gauge
             alias: kafka.request.produce.failed
     - include:
-        domain: '"kafka.network"'
-        bean: '"kafka.network":type="RequestMetrics",name="Produce-TotalTimeMs"'
+        domain: 'kafka.network'
+        bean: 'kafka.network:type=RequestMetrics,name=TotalTimeMs,request=Produce'
         attribute:
           Mean:
             metric_type: gauge
@@ -72,8 +86,8 @@ init_config:
             metric_type: gauge
             alias: kafka.request.produce.time.99percentile
     - include:
-        domain: '"kafka.network"'
-        bean: '"kafka.network":type="RequestMetrics",name="Fetch-TotalTimeMs"'
+        domain: 'kafka.network'
+        bean: 'kafka.network:type=RequestMetrics,name=TotalTimeMs,request=Fetch'
         attribute:
           Mean:
             metric_type: gauge
@@ -82,8 +96,8 @@ init_config:
             metric_type: gauge
             alias: kafka.request.fetch.time.99percentile
     - include:
-        domain: '"kafka.network"'
-        bean: '"kafka.network":type="RequestMetrics",name="UpdateMetadata-TotalTimeMs"'
+        domain: 'kafka.network'
+        bean: 'kafka.network:type=RequestMetrics,name=TotalTimeMs,request=UpdateMetadata'
         attribute:
           Mean:
             metric_type: gauge
@@ -92,8 +106,8 @@ init_config:
             metric_type: gauge
             alias: kafka.request.update_metadata.time.99percentile
     - include:
-        domain: '"kafka.network"'
-        bean: '"kafka.network":type="RequestMetrics",name="Metadata-TotalTimeMs"'
+        domain: 'kafka.network'
+        bean: 'kafka.network:type=RequestMetrics,name=TotalTimeMs,request=Metadata'
         attribute:
           Mean:
             metric_type: gauge
@@ -102,43 +116,50 @@ init_config:
             metric_type: gauge
             alias: kafka.request.metadata.time.99percentile
     - include:
-        domain: '"kafka.network"'
-        bean: '"kafka.network":type="RequestMetrics",name="Offsets-TotalTimeMs"'
+        domain: 'kafka.network'
+        bean: 'kafka.network:type=RequestMetrics,name=TotalTimeMs,request=Offsets'
         attribute:
           Mean:
             metric_type: gauge
             alias: kafka.request.offsets.time.avg
           99thPercentile:
             metric_type: gauge
             alias: kafka.request.offsets.time.99percentile
+    - include:
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=KafkaRequestHandlerPool,name=RequestHandlerAvgIdlePercent'
+        attribute:
+          MeanRate:
+            metric_type: gauge
+            alias: kafka.request.handler.avg.idle.pct
 
     #
     # Replication stats
     #
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="ReplicaManager",name="ISRShrinksPerSec"'
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=ReplicaManager,name=IsrShrinksPerSec'
         attribute:
           MeanRate:
             metric_type: gauge
             alias: kafka.replication.isr_shrinks
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="ReplicaManager",name="ISRExpandsPerSec"'
+        domain: 'kafka.server'
+        bean: 'kafka.server:type=ReplicaManager,name=IsrExpandsPerSec'
         attribute:
           MeanRate:
             metric_type: gauge
             alias: kafka.replication.isr_expands
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="ControllerStats",name="LeaderElectionRateAndTimeMs"'
+        domain: 'kafka.controller'
+        bean: 'kafka.controller:type=ControllerStats,name=LeaderElectionRateAndTimeMs'
         attribute:
           MeanRate:
             metric_type: gauge
             alias: kafka.replication.leader_elections
     - include:
-        domain: '"kafka.server"'
-        bean: '"kafka.server":type="ControllerStats",name="UncleanLeaderElectionsPerSec"'
+        domain: 'kafka.controller'
+        bean: 'kafka.controller:type=ControllerStats,name=UncleanLeaderElectionsPerSec'
         attribute:
           MeanRate:
             metric_type: gauge
@@ -148,8 +169,8 @@ init_config:
     # Log flush stats
     #
     - include:
-        domain: '"kafka.log"'
-        bean: '"kafka.log":type="LogFlushStats",name="LogFlushRateAndTimeMs"'
+        domain: 'kafka.log'
+        bean: 'kafka.log:type=LogFlushStats,name=LogFlushRateAndTimeMs'
         attribute:
           MeanRate:
             metric_type: gauge