Correct argument name is `send_timeout_millis` not `send_timeout_seconds`

Fixes #7863

### Motivation
1) Topic level policy will be overwritten by namespace level
2) After removing the topic level policy, `DispatchLimiter` does not take effect,  the namespace level policy should be used

### Modifications
1）If there is a topic-level policy, it will not be overwritten by the namespace-level policy when the policy is updated
2）When removing topic-level policy, namespace-level policy will be used. If the namespace-level policy does not exist, the broker level will be used

### Verifying this change
unit test:
TopicPoliciesTest#testPolicyOverwrittenByNamespaceLevel

The pulsar docker and pulsar standalone docker image build failed by:
```
Processing ./pulsar-client/pulsar_client-2.6.0-cp27-cp27mu-manylinux1_x86_64.whl
2020-08-25T02:23:28.9567844Z [INFO] Collecting fastavro
2020-08-25T02:23:29.0080316Z [INFO]   Downloading fastavro-1.0.0.tar.gz (658 kB)
2020-08-25T02:23:29.3108074Z [INFO]     ERROR: Command errored out with exit status 1:
2020-08-25T02:23:29.3109489Z [INFO]      command: /usr/bin/python2.7 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-jvZueR/fastavro/setup.py'"'"'; __file__='"'"'/tmp/pip-install-jvZueR/fastavro/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-iH1mMy
2020-08-25T02:23:29.3110061Z [INFO]          cwd: /tmp/pip-install-jvZueR/fastavro/
2020-08-25T02:23:29.3110303Z [INFO]     Complete output (5 lines):
2020-08-25T02:23:29.3110520Z [INFO]     Traceback (most recent call last):
2020-08-25T02:23:29.3110741Z [INFO]       File "<string>", line 1, in <module>
2020-08-25T02:23:29.3111190Z [INFO]       File "/tmp/pip-install-jvZueR/fastavro/setup.py", line 58, in <module>
2020-08-25T02:23:29.3111437Z [INFO]         if sys.implementation.name != "pypy":
2020-08-25T02:23:29.3111886Z [INFO]     AttributeError: 'module' object has no attribute 'implementation'
```

I remove the python2.7 and using the python3 to build images.

* Remove python2 in images

* Remove python2 stuff

* Update the default python version

Signed-off-by: Nxiaolong.ran <rxl@apache.org>

### Motivation

```
$ mvn dependency:tree|grep vertx
```

Output:
```
[INFO] +- org.apache.bookkeeper.http:vertx-http-server:jar:4.10.0:compile
[INFO] +- io.vertx:vertx-core:jar:3.5.3:compile
[INFO] +- io.vertx:vertx-web:jar:3.5.3:compile
[INFO] |  +- io.vertx:vertx-auth-common:jar:3.5.3:compile
[INFO] |  \- io.vertx:vertx-bridge-common:jar:3.5.3:compile
[INFO] |  +- org.apache.bookkeeper.http:vertx-http-server:jar:4.10.0:provided
[INFO] |  +- io.vertx:vertx-core:jar:3.5.3:provided
[INFO] |  \- io.vertx:vertx-web:jar:3.5.3:provided
[INFO] |     +- io.vertx:vertx-auth-common:jar:3.5.3:provided
[INFO] |     \- io.vertx:vertx-bridge-common:jar:3.5.3:provided
```

### Modifications

- exclude `vertx` from bookkeeper-http package and include vertx of `3.5.3` to `vertx-http-server`

Signed-off-by: Nxiaolong.ran <rxl@apache.org>

### Modifications

- Upgrade `protobuf` version to `3.11.4`

Fixes #7476 

### Motivation

In some situations,  discovery service can't find active broker while all brokers are running well.  This PR will update from zookeeper if available broker list is empty to avoid  "No active broker is available"  `RestException` happen.


### Modifications

double check from zookeeper if availableBrokers is empty

* Small documentation improvements and clarifications around AuthN / AuthZ

* PR feedback and added some clarifications

Fixes #7925 

Master Issue: #<xyz>

### Motivation

 This PR fix publish buffer of one ServerCnx caculated multi-times when check broker's publish buffer.

### Modifications

 check publish buffer of broker by adding messagePublishBufferSize of a ServerCnx for only one time.

Fixes #7928

### Motivation

As https://nvd.nist.gov/vuln/detail/CVE-2017-18640 said, the `snakeyaml` < 1.26

### Modifications

In `pulsar-functions` model:

- The `snakeyaml` 1.19 appears to be included from dependency on org.apache.pulsar:pulsar-functions-secrets:jar:2.6.1 based on included dependency of io.kubernetes:client-java-api:jar:2.0.0:compile Fixed in 9.0.2

- The `snakeyaml` 1.16 appears to be included from the dependency on org.apache.pulsar:pulsar-functions-instance:jar:2.6.1 based on io.prometheus.jmx:collector:jar:0.12.0 Fixed in 0.13.0

- The 1.17 org.apache.pulsar.tests:integration:test-jar:tests:2.6.1:test depends on org.elasticsearch.client:elasticsearch-rest-high-level-client:jar:6.3.2:test Fixed in elasticsearch >= 7.7.1 (7.9.1 current)

Fixes https://github.com/streamnative/pulsar/issues/1314

### Motivation

Currently, the transaction ack abort process is not well.

### Modifications

Make some changes for the transaction ack abort process.

Motivation
The state is not production-ready.

Modifications
Remove the note about stateful function from the Deploy a cluster on bare metal document.

updated docs for releases: master ~ 2.1.0

Fix [https://github.com/apache/pulsar/issues/7759](https://github.com/apache/pulsar/issues/7759), and master issue [https://github.com/apache/pulsar/issues/2688](https://github.com/apache/pulsar/issues/2688)

### Motivation

Support set/get/remove maxConsumers on a topic level.

Fixes #7895

### Motivation
For get-internal-stats of persistent topic admin cli: https://pulsar.apache.org/docs/en/2.6.0/admin-api-persistent-topics/#get-internal-stats, we can also return the compacted topic ledger id if compaction is enabled. So we'll able to read from ledger without creating additional subscription, it can benefit like querying compacted topic from Pulsar SQL.

### Modifications
Expose CompactedTopicContext from CompactedTopicImpl, try to get ledger information of compacted topic ledger if exist in PersistentTopic.

### Verifying this change

This change added tests and can be verified as follows:
- Added unit test to verify correct compacted ledger info is returned after compaction.


* Report compacted topic ledger info when calling get internal stats.

* Update documentation to add information about returning compacted topic ledger when get-internal-stats.

Add bookkeeperClientMinNumRacksPerWriteQuorum, bookkeeperClientEnforceMinNumRacksPerWriteQuorum conf options (#7977)

Added bookkeeperClientMinNumRacksPerWriteQuorum and bookkeeperClientEnforceMinNumRacksPerWriteQuorum to be able to configure rack and region aware bookie selection policy more precisely.

Motivation
We have Apache Pulsar setup running on Azure in 3 different Availability Zones (2 bookkeepers per zone). We wanted to store copy of each pulsar message in all that AZs. After configuring rack aware bookie selection policy, we found that messages are usually stored only in 2 AZs. After digging, we've found that it's caused by default bookeeper client minNumRacksPerWriteQuorum=2 setting. We've added bookkeeperClientMinNumRacksPerWriteQuorum and also bookkeeperClientEnforceMinNumRacksPerWriteQuorum to be able to configure this behaviour.

Modifications
Added bookkeeperClientMinNumRacksPerWriteQuorum and bookkeeperClientEnforceMinNumRacksPerWriteQuorum configuration option, modified tests, config files and documentation.

Verifying this change
We've updated existing unit tests, deployed modified pulsar docker image on AKS kubernetes cluster using helm charts and checked that stored messages were written always to bookkeepers in all AZs.


* Added `bookkeeperClientMinNumRacksPerWriteQuorum` and `bookkeeperClientEnforceMinNumRacksPerWriteQuorum` broker configuration options to be able set `minNumRacksPerWriteQuorum` and `enforceMinNumRacksPerWriteQuorum` bookkeeper client options.

* Reverted accidental change in ServiceConfigurationTest.
Co-authored-by: NMichal Koziorowski <Michal.Koziorowski@tomtom.com>

Co-authored-by: NJerry Peng <jerryp@splunk.com>

Co-authored-by: NJerry Peng <jerryp@splunk.com>

### Motivation
Support topic-level inactiveTopicPolicies

### Modifications
Support set/get/remove inactiveTopicPolicies policy on topic level.

* Add docs of package Pulsar Functions
Signed-off-by: Nxiaolong.ran <rxl@apache.org>

Fix https://github.com/streamnative/pulsar/issues/1307

Master Issue: #2664 

### Motivation

Handle acknowledge in the transaction.

### Modifications

1. Register subscription to the transaction metadata store.
2. Make the ack command carry the transaction information.
3. When committing a transaction, commit every subscription in the transaction.

### Motivation
Support set Offload Policy on topic level

### Modifications
Support set/get/remove Offload policy on topic level.

### Verifying this change
Added Unit test to verify set/get/remove Offload policy at Topic level work as expected when Topic level policy is enabled/disabled
`org.apache.pulsar.broker.admin.AdminApiOffloadTest#testOffloadPoliciesApi`
`org.apache.pulsar.broker.admin.AdminApiOffloadTest#testTopicLevelOffload`

* Various fixes for Batch Source
1. Create intermediate topic/subscription prior to function running in case auto topic creation is turned off
2. Fix possible NPE in CronTrigger when calling stop()
3. Stop all producers created in ContextImpl
4. Delete intermediate topic for batch source
Co-authored-by: NJerry Peng <jerryp@splunk.com>

Fixes #7920

### Motivation
set/get/remove deduplication policy is on topic level. But the pulsar admin cli java doc is not supported accordingly.

Motivation
Website admin cli link error
Modifications
Update link version
Verifying this change
Local test

Co-authored-by: NTakesi Kimura <takeshki@yahoo-corp.jp>

Fixes #7799

### Motivation
Pulsar metrics providing wrong information

### Modifications
add a reset for counter

Link [https://github.com/apache/pulsar/issues/7758](https://github.com/apache/pulsar/issues/7758) and master issue [https://github.com/apache/pulsar/issues/2688](https://github.com/apache/pulsar/issues/2688)

### Motivation

Support set/get/remove maxProducers on a topic level.

### Motivation
PR #7818 #7802 supports topic-level policies.
But the pulsar admin cli java doc is not supported accordingly.

Co-authored-by: NJerry Peng <jerryp@splunk.com>

[pulsar-broker] Stop to dispatch when skip message temporally since Key_Shared consumer stuck on delivery (#7553)

### Motivation
In some case of Key_Shared consumer, messages ordering was broken.
Here is how to reproduce(I think it is one of case to reproduce this issue).

1. Connect Consumer1 to Key_Shared subscription `sub` and stop to receive
   - receiverQueueSize: 500
2. Connect Producer and publish 500 messages with key `(i % 10)`
3. Connect Consumer2 to same subscription and start to receive
   - receiverQueueSize: 1
   - since https://github.com/apache/pulsar/pull/7106 , Consumer2 can't receive (expected)
4. Producer publish more 500 messages with same key generation algorithm
5. After that, Consumer1 start to receive
6. Check Consumer2 message ordering
   - sometimes message ordering was broken in same key

Consumer1:
```
Connected: Tue Jul 14 09:36:39 JST 2020
[pulsar-client-io-1-1] WARN com.scurrilous.circe.checksum.Crc32cIntChecksum - Failed to load Circe JNI library. Falling back to Java based CRC32c provider
[pulsar-timer-4-1] INFO org.apache.pulsar.client.impl.ConsumerStatsRecorderImpl - [persistent://public/default/key-shared-test] [sub0] [820f0] Prefetched messages: 499 --- Consume throughput received: 0.02 msgs/s --- 0.00 Mbit/s --- Ack sent rate: 0.00 ack/s --- Failed messages: 0 --- batch messages: 0 ---Failed acks: 0
Received: my-message-0 PublishTime: 1594687006203 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-1 PublishTime: 1594687006243 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-2 PublishTime: 1594687006247 Date: Tue Jul 14 09:37:46 JST 2020
...
Received: my-message-498 PublishTime: 1594687008727 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-499 PublishTime: 1594687008731 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-500 PublishTime: 1594687038742 Date: Tue Jul 14 09:37:46 JST 2020
...
Received: my-message-990 PublishTime: 1594687040094 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-994 PublishTime: 1594687040103 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-995 PublishTime: 1594687040105 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-997 PublishTime: 1594687040113 Date: Tue Jul 14 09:37:46 JST 2020
```

Consumer2:
```
Connected: Tue Jul 14 09:37:03 JST 2020
[pulsar-client-io-1-1] WARN com.scurrilous.circe.checksum.Crc32cIntChecksum - Failed to load Circe JNI library. Falling back to Java based CRC32c provider
Received: my-message-501 MessageId: 4:1501:-1 PublishTime: 1594687038753 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-502 MessageId: 4:1502:-1 PublishTime: 1594687038755 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-503 MessageId: 4:1503:-1 PublishTime: 1594687038759 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-506 MessageId: 4:1506:-1 PublishTime: 1594687038785 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-508 MessageId: 4:1508:-1 PublishTime: 1594687038812 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-901 MessageId: 4:1901:-1 PublishTime: 1594687039871 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-509 MessageId: 4:1509:-1 PublishTime: 1594687038815 Date: Tue Jul 14 09:37:46 JST 2020
ordering was broken, key: 1 oldNum: 901 newNum: 511
Received: my-message-511 MessageId: 4:1511:-1 PublishTime: 1594687038826 Date: Tue Jul 14 09:37:46 JST 2020
Received: my-message-512 MessageId: 4:1512:-1 PublishTime: 1594687038830 Date: Tue Jul 14 09:37:46 JST 2020
...
```

I think this issue is caused by https://github.com/apache/pulsar/pull/7105.
Here is an example.
1. dispatch messages
2. Consumer2 was stuck and `totalMessagesSent=0`
   - Consumer2 availablePermits was 0
3. skip redeliver messages temporally
   - Consumer2 availablePermits was back to 1
4. dispatch new messages
   - new message was dispatched to Consumer2
5. back to redeliver messages
4. dispatch messages
   - ordering was broken

### Modifications
Stop to dispatch when skip message temporally since Key_Shared consumer stuck on delivery.

Fixes https://github.com/streamnative/pulsar/issues/1312

# Motivation

Currently, the transaction abort on partitions operation is not getting through.

### Modifications

Make the transaction abort on partitions operation get through.

[Issue 7864][docs]Update document for how to pick active consumer for failover subscription. (#7917)

Update document to specify how active consumer is picked for partitioned and non-partitoned topic for failover subscription mode. The change was push in 2.4.2 but document has not been updated.

Fixes #7864

**Motivation**

After #7813, the python client supports the oauth2 authentication as well. Add an example for it.

[Issue 7933][pulsar-broker-common] Add some logging to improve Authentication debugging and Fix typos in code "occured" -> "occurred" (#7934)

Fixes #7933 

### Motivation
Newbie trying to make his first contribution to this projection :-)

### Modifications

Added some logging to Authentication Service to help debugging when there are more than one AuthN provider.
When I did that I noticed a typo ('occured' should have two r's) so I decided to try to fix all of them

Modifications
Support set publish rate on topic level.
Support get publish rate on topic level.
Support remove publish rate on topic level.

Signed-off-by: Nxiaolong.ran <rxl@apache.org>

* Add Pulsar Summit CFP blog

* update

* Update 2020-08-25-pulsar-summit-asia-2020-cfp.md

Signed-off-by: Nxiaolong.ran <rxl@apache.org>

### Modifications

Fix the time of release 2.6.1 to `08/21`