This patch makes two improvements to internal metadata handling logic and testing:
1. It reduce dependence on the public object `Cluster` for internal metadata propagation since it is not easy to evolve. As an example, we need to propagate leader epochs from the metadata response to `Metadata`, but it is not straightforward to do this without exposing it in `PartitionInfo` since that is what `Cluster` uses internally. By doing this change, we are able to remove some redundant `Cluster` building logic.
2. We want to make the metadata handling in `MockClient` simpler and more consistent. Currently we have mix of metadata update mechanisms which are internally inconsistent with each other and do not match the implementation in `NetworkClient`.
Reviewers: Rajini Sivaram <rajinisivaram@googlemail.com>
KIP-368 implementation to enable periodic re-authentication of SASL clients. Also adds a broker configuration option to terminate client connections that do not re-authenticate within the configured interval.
Adds `client.dns.lookup=resolve_canonical_bootstrap_servers_only` option to perform full dns resolution of bootstrap addresses
Reviewers: Colin Patrick McCabe <colin@cmccabe.xyz>, Sriharsha Chintalapani <sriharsha@apache.org>, Edoardo Comar <ecomar@uk.ibm.com>, Mickael Maison <mickael.maison@gmail.com>, Manikumar Reddy <manikumar.reddy@gmail.com>, Rajini Sivaram <rajinisivaram@googlemail.com>
Implementation of KIP-302: Based on the new client configuration `client.dns.lookup`, a NetworkClient can use InetAddress.getAllByName to find all IPs and iterate over them when they fail to connect. Only uses either IPv4 or IPv6 addresses similar to the default mode.
Co-authored-by: Edoardo Comar <ecomar@uk.ibm.com>
Co-authored-by: Mickael Maison <mickael.maison@gmail.com>
Reviewers: Rajini Sivaram <rajinisivaram@googlemail.com>
- SslFactoryTest should use SslFactory to create SSLEngine
- Use Mockito instead of EasyMock in `ConsoleConsumerTest` as one of
the tests mocks a standard library class and the latest released EasyMock
version can't do that when Java 11 is used.
- Avoid mocking `ConcurrentMap` in `SourceTaskOffsetCommitterTest`
for similar reasons. As it happens, mocking is not actually needed here.
Reviewers: Rajini Sivaram <rajinisivaram@googlemail.com>
The parent classloader of the DelegatingClassLoader and therefore the classloading scheme used by Connect does not have to be fixed to the System classloader.
Setting it the same as the one that was used to load the DelegatingClassLoader class itself is more flexible and, while in most cases will result in the System classloader to be used, it will also work in othr managed environments that control classloading differently (OSGi, and others).
The fix is minimal and the mainstream use is tested via system tests.
Reviewers: Randall Hauch <rhauch@gmail.com>, Jason Gustafson <jason@confluent.io>
Various converters (AvroConverter and JsonConverter) produce a
SchemaAndValue consisting of a logical schema type and a java.util.Date.
This is a fix for SchemaProjector to properly handle the Date.
Author: Robert Yokota <rayokota@gmail.com>
Reviewers: Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5736 from rayokota/KAFKA-7476
Allow to cast LogicalType to string by calling the serialized (Java) object's toString().
Added tests for `BigDecimal` and `Date` as whole record and as fields.
Author: Amit Sela <amitsela33@gmail.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Robert Yokota <rayokota@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#4820 from amitsela/cast-transform-bytes
Switches to normal year format instead of week date years and day of month instead of day of year.
This is directly from #4820, but separated into a different JIRA/PR to keep the fixes independent. Original authorship should be maintained in the commit.
Author: Amit Sela <amitsela33@gmail.com>
Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5718 from ewencp/fix-header-converter-date-format
*More detailed description of your change,
if necessary. The PR title and PR message become
the squashed commit message, so use a separate
comment to ping reviewers.*
*Summary of testing strategy (including rationale)
for the feature or bug fix. Unit and/or integration
tests are expected for any behaviour change and
system tests should be considered for larger changes.*
Author: Michał Borowiecki <mbor81@gmail.com>
Reviewers: Arjun Satish <arjun@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5700 from mihbor/KAFKA-7434
Modified several classes' `equals` methods and simplified a complex method to
reduce the NPath complexity so they could be removed from the checkstyle
suppressions that were required with the recent move to Java 8 and upgrade
of Checkstyle: https://github.com/apache/kafka/pull/5046.
Reviewers: Robert Yokota <rayokota@gmail.com>, Arjun Satish <arjun@confluent.io>, Ismael Juma <ismael@juma.me.uk>
findBugs is abandoned, it doesn't work with Java 9 and the Gradle plugin will be deprecated in
Gradle 5.0: https://github.com/gradle/gradle/pull/6664
spotBugs is actively maintained and it supports Java 8, 9 and 10. Java 11 is not supported yet,
but it's likely to happen soon.
Also fixed a file leak in Connect identified by spotbugs.
Manually tested spotBugsMain, jarAll and importing kafka in IntelliJ and running
a build in the IDE.
Author: Ismael Juma <ismael@juma.me.uk>
Reviewers: Colin Patrick McCabe <colin@cmccabe.xyz>, Dong Lin <lindong28@gmail.com>
Closes#5625 from ijuma/kafka-5887-spotbugs
Replace 'this' reference in anonymous inner class logs to out class's 'this'
Author: Kevin Lafferty <kevin.lafferty@gmail.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Arjun Satish <arjun@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5583 from kevin-laff/connect_logging
During actions such as a reconfiguration, the task configs are obtained
via `Worker.connectorTaskConfigs` and then subsequently saved into an
instance of `ClusterConfigState`. The values of the properties that are saved
are post-transformation (of variable references) when they should be
pre-transformation. This is to avoid secrets appearing in plaintext in
the `connect-configs` topic, for example.
The fix is to change the 2 clients of `Worker.connectorTaskConfigs` to
perform a reverse transformation (values converted back into variable
references) before saving them into an instance of `ClusterConfigState`.
The 2 places where the save is performed are
`DistributedHerder.reconfigureConnector` and
`StandaloneHerder.updateConnectorTasks`.
The way that the reverse transformation works is by using the
"raw" connector config (with variable references still intact) from
`ClusterConfigState` to convert config values back into variable
references for those keys that are common between the task config
and the connector config.
There are 2 additional small changes that only affect `StandaloneHerder`:
1) `ClusterConfigState.allTasksConfigs` has been changed to perform a
transformation (resolution) on all variable references. This is
necessary because the result of this method is compared directly to
`Worker.connectorTaskConfigs`, which also has variable references
resolved.
2) `StandaloneHerder.startConnector` has been changed to match
`DistributedHerder.startConnector`. This is to fix an issue where
during `StandaloneHerder.restartConnector`, the post-transformed
connector config would be saved back into `ClusterConfigState`.
I also performed an analysis of all other code paths where configs are
saved back into `ClusterConfigState` and did not find any other
issues.
Author: Robert Yokota <rayokota@gmail.com>
Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5475 from rayokota/KAFKA-7242-reverse-xform-props
Currently logical types are dropped during Cast Transformation.
This patch fixes this behaviour.
Reviewers: Randall Hauch <rhauch@gmail.com>, Jason Gustafson <jason@confluent.io>
In AK's documentation, the config props for connectors are not listed (https://kafka.apache.org/documentation/#connectconfigs). This PR adds these sink and source connector configs to the html site-docs.
Signed-off-by: Arjun Satish <arjunconfluent.io>
Author: Arjun Satish <arjun@confluent.io>
Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5469 from wicknicks/add-connector-configs-to-docs
If a property requires validation, it should be pretransformed if it is a variable reference, in order to have a value that will properly pass the validation.
Author: Robert Yokota <rayokota@gmail.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5445 from rayokota/KAFKA-7225-pretransform-validated-props
We currently do a lot of bookkeeping for timeouts which is both error-prone and distracting. This patch adds a new `Timer` class to simplify this logic and control unnecessary calls to system time. In particular, this helps with nested timeout operations. The consumer has been updated to use the new class.
Reviewers: Ismael Juma <ismael@juma.me.uk>, Guozhang Wang <wangguoz@gmail.com>
DLQ reporter does not get a `errorHandlingMetrics` object when created by the worker. This results in an NPE.
Signed-off-by: Arjun Satish <arjunconfluent.io>
*More detailed description of your change,
if necessary. The PR title and PR message become
the squashed commit message, so use a separate
comment to ping reviewers.*
*Summary of testing strategy (including rationale)
for the feature or bug fix. Unit and/or integration
tests are expected for any behaviour change and
system tests should be considered for larger changes.*
Author: Arjun Satish <arjun@confluent.io>
Reviewers: Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5440 from wicknicks/KAFKA-7228
Use delivery timeout instead of retries when possible and remove various TODOs associated with completion of KIP-91.
Reviewers: Ismael Juma <ismael@juma.me.uk>, Guozhang Wang <wangguoz@gmail.com>
A recent change from `new FileOutputStream` to `Files.newOutputStream` missed the `CREATE` flag (which is necessary in addition to `APPEND`).
Reviewers: Ismael Juma <ismael@juma.me.uk>
They rely on finalizers (before Java 11), which create
unnecessary GC load. The alternatives are as easy to
use and don't have this issue.
Also use FileChannel directly instead of retrieving
it from RandomAccessFile whenever possible
since the indirection is unnecessary.
Finally, add a few try/finally blocks.
Reviewers: Colin Patrick McCabe <colin@cmccabe.xyz>, Rajini Sivaram <rajinisivaram@googlemail.com>
https://issues.apache.org/jira/browse/KAFKA-7058
* Summary of testing strategy: Added new unit test
Author: Gunnar Morling <gunnar.morling@googlemail.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5225 from gunnarmorling/KAFKA-7058
This was originally missed when headers were added as part of KIP-145 in AK 1.1. An additional unit test was added in line with the StringConverter.
This should be backported to the AK `1.1` branch so that it is included in the next bugfix release. The `SimpleHeaderConverter` class that we're referencing was first added in the 1.1.0 release, so there's no reason to backport earlier.
Author: Randall Hauch <rhauch@gmail.com>
Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5204 from rhauch/kafka-7047
Create an instance of the plugin only it's a Versioned Plugin. Prior to KIP-285, this was done for only for Connector and this PR will continue to have the same behavior.
Author: Magesh Nandakumar <magesh.n.kumar@gmail.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5191 from mageshn/KAFKA-7039
KIP-305 added numeric converters to Connect, but these were added in Connect’s API module in the same package as the `StringConverter`. This commit moves them into the Runtime module and into the `converters` package where the `ByteArrayConverter` already lives. These numeric converters have not yet been included in a release, and so they can be moved without concern.
All of Connect’s converters must be referenced in worker / connector configurations and are therefore part of the API, but otherwise do not need to be in the “api” module as they do not need to be instantiated or directly used by extensions. This change makes them more similar to and aligned with the `ByteArrayConverter`.
It also gives us the opportunity to move them into the “api” module in the future (keeping the same package name), should we ever want or need to do so. However, if we were to start out with them in the “api” module, we would never be able to move them out into the “runtime” module, even if we kept the same package name. Therefore, moving them to “runtime” now gives us a bit more flexibility.
This PR moves the unit tests for the numeric converters accordingly, and updates the `PluginsUtil` and `PluginUtilsTest` as well.
Author: Randall Hauch <rhauch@gmail.com>
Reviewers: Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5222 from rhauch/kafka-7056
Several recently-added converters are included in the plugin isolation whitelist, similarly to the `StringConverter`. This is a change in the implementation, and does not affect the approved KIP. Several unit tests were added to verify they are being loaded in isolation, again similarly to `StringConverter`.
These changes should be applied only to `trunk` and `2.0`, since these converters were added as part of KIP-305 for AK 2.0.
Author: Randall Hauch <rhauch@gmail.com>
Reviewers: Magesh Nandakumar <magesh.n.kumar@gmail.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5198 from rhauch/kafka-7043
After [3173](https://github.com/apache/kafka/commit/e0150a25e8), the field "activePaths" is not used anymore.
Author: Chia-Ping Tsai <chia7712@gmail.com>
Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>
Closes#4984 from chia7712/remove_unused_field_from_DelegatingClassLoader
This moves FileConfigProvider to the org.apache.common.config.provider package to more easily isolate provider implementations going forward.
Reviewers: Konstantine Karantasis <konstantine@confluent.io>, Randall Hauch <rhauch@gmail.com>, Ismael Juma <ismael@juma.me.uk>, Jason Gustafson <jason@confluent.io>
If the property `errors.deadletterqueue.context.headers.enable` is set to true, add a set of headers to the message describing the context under which the error took place.
A unit test is added to check the correctness of header creation.
Signed-off-by: Arjun Satish <arjunconfluent.io>
Author: Arjun Satish <arjun@confluent.io>
Reviewers: Konstantine Karantasis <konstantine@confluent.io>, Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5159 from wicknicks/KAFKA-7003
Currently, the replication factor is hardcoded to a value of 3. This means that we cannot use a DLQ in any cluster setup with less than three brokers. It is better to have the user specify this value if the default value does meet the requirements.
Testing: A unit test is added.
Signed-off-by: Arjun Satish <arjunconfluent.io>
Author: Arjun Satish <arjun@confluent.io>
Reviewers: Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5145 from wicknicks/KAFKA-7002
Fix ServiceLoader issue with PluginClassLoader and add basic-auth-extension packaging & classpath
*More detailed description of your change,
if necessary. The PR title and PR message become
the squashed commit message, so use a separate
comment to ping reviewers.*
*Summary of testing strategy (including rationale)
for the feature or bug fix. Unit and/or integration
tests are expected for any behaviour change and
system tests should be considered for larger changes.*
Author: Magesh Nandakumar <magesh.n.kumar@gmail.com>
Reviewers: Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5135 from mageshn/KAFKA-6991
This is a small change to use the Java ServiceLoader to load ConfigProvider plugins. It uses code added by mageshn for Connect Rest Extensions.
Author: Robert Yokota <rayokota@gmail.com>
Reviewers: Magesh Nandakumar <magesh.n.kumar@gmail.com>, Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5141 from rayokota/service-loader-for-config-plugins
Move the error handling configuration properties into the ConnectorConfig and SinkConnectorConfig classes, and refactor the tests and classes to use these new properties.
Testing: Unit tests and running the connect-standalone script with a file sink connector.
Author: Arjun Satish <arjun@confluent.io>
Author: Randall Hauch <rhauch@gmail.com>
Reviewers: Konstantine Karantasis <konstantine@confluent.io>, Magesh Nandakumar <magesh.n.kumar@gmail.com>, Robert Yokota <rayokota@gmail.com>, Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5125 from wicknicks/KAFKA-6981
This commit allows secrets in Connect configs to be externalized and replaced with variable references of the form `${provider:[path:]key}`, where the "path" is optional.
There are 2 main additions to `org.apache.kafka.common.config`: a `ConfigProvider` and a `ConfigTransformer`. The `ConfigProvider` is an interface that allows key-value pairs to be provided by an external source for a given "path". An a TTL can be associated with the key-value pairs returned from the path. The `ConfigTransformer` will use instances of `ConfigProvider` to replace variable references in a set of configuration values.
In the Connect framework, `ConfigProvider` classes can be specified in the worker config, and then variable references can be used in the connector config. In addition, the herder can be configured to restart connectors (or not) based on the TTL returned from a `ConfigProvider`. The main class that performs restarts and transformations is `WorkerConfigTransformer`.
Finally, a `configs()` method has been added to both `SourceTaskContext` and `SinkTaskContext`. This allows connectors to get configs with variables replaced by the latest values from instances of `ConfigProvider`.
Most of the other changes in the Connect framework are threading various objects through classes to enable the above functionality.
Author: Robert Yokota <rayokota@gmail.com>
Author: Ewen Cheslack-Postava <me@ewencp.org>
Reviewers: Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5068 from rayokota/KAFKA-6886-connect-secrets
This PR implements the features described in this KIP: https://cwiki.apache.org/confluence/display/KAFKA/KIP-298%3A+Error+Handling+in+Connect
This PR changes the Connect framework to allow it to automatically deal with errors encountered while processing records in a Connector. The following behavior changes are introduced here:
**Retry on Failure**: Retry the failed operation a configurable number of times, with backoff between each retry.
**Task Tolerance Limits**: Tolerate a configurable number of failures in a task.
We also add the following ways to report errors, along with sufficient context to simplify the debugging process:
**Log Error Context**: The error information along with processing context is logged along with standard application logs.
**Dead Letter Queue**: Produce the original message into a Kafka topic (applicable only to sink connectors).
New **metrics** which will monitor the number of failures, and the behavior of the response handler are added.
The changes proposed here **are backward compatible**. The current behavior in Connect is to kill the task on the first error in any stage. This will remain the default behavior if the connector does not override any of the new configurations which are provided as part of this feature.
Testing: added multiple unit tests to test the retry and tolerance logic.
Author: Arjun Satish <arjun@confluent.io>
Author: Ewen Cheslack-Postava <me@ewencp.org>
Reviewers: Magesh Nandakumar <magesh.n.kumar@gmail.com>, Randall Hauch <rhauch@gmail.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5065 from wicknicks/KAFKA-6378
This PR provides the implementation for KIP-285 and also a reference implementation for authenticating BasicAuth credentials using JAAS LoginModule
Author: Magesh Nandakumar <magesh.n.kumar@gmail.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Arjun Satish <wicknicks@users.noreply.github.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#4931 from mageshn/KIP-285
*[KIP-305](https://cwiki.apache.org/confluence/display/KAFKA/KIP-305%3A+Add+Connect+primitive+number+converters) has been approved.*
Added converters and header converters for the primitive number types for which Kafka already had serializers and deserializers. All extend a common base class, `NumberConverter`, that encapsulates most of the shared functionality. Unit tests were added to check the basic functionality.
These classes are not used by any other Connect code, and must be explicitly used in Connect workers and connectors.
Author: Randall Hauch <rhauch@gmail.com>
Reviewers: Arjun Satish <wicknicks@users.noreply.github.com>, Magesh Nandakumar <magesh.n.kumar@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5034 from rhauch/kafka-6913
Implementation of [KIP-174](https://cwiki.apache.org/confluence/display/KAFKA/KIP-174+-+Deprecate+and+remove+internal+converter+configs+in+WorkerConfig)
Configuration properties 'internal.key.converter' and 'internal.value.converter'
are deprecated, and default to org.apache.kafka.connect.json.JsonConverter.
Warnings are logged if values are specified for either, or if properties that
appear to configure instances of internal converters (i.e., ones prefixed with
either 'internal.key.converter.' or 'internal.value.converter.') are given.
The property 'schemas.enable' is also defaulted to false for internal
JsonConverter instances (both for keys and values) if it isn't specified.
Documentation and code have also been updated with deprecation notices and
annotations, respectively.
Unit tests have been updated in `PluginsTest` to account for the new defaults for `schemas.enable` for internal key/value converters, and to ensure that (for the time being), internal key/value converters are still configurable despite being deprecated.
Author: Chris Egerton <chrise@confluent.io>
Author: Ewen Cheslack-Postava <me@ewencp.org>
Reviewers: Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#4693 from C0urante/kafka-5540
Add the new stricter-timeout version of `poll` proposed in KIP-266.
The pre-existing variant `poll(long timeout)` would block indefinitely for metadata
updates if they were needed, then it would issue a fetch and poll for `timeout` ms
for new records. The initial indefinite metadata block caused applications to become
stuck when the brokers became unavailable. The existence of the timeout parameter
made the indefinite block especially unintuitive.
This PR adds `poll(Duration timeout)` with the semantics:
1. iff a metadata update is needed:
1. send (asynchronous) metadata requests
2. poll for metadata responses (counts against timeout)
- if no response within timeout, **return an empty collection immediately**
2. if there is fetch data available, **return it immediately**
3. if there is no fetch request in flight, send fetch requests
4. poll for fetch responses (counts against timeout)
- if no response within timeout, **return an empty collection** (leaving async fetch request for the next poll)
- if we get a response, **return the response**
The old method, `poll(long timeout)` is deprecated, but we do not change its semantics, so it remains:
1. iff a metadata update is needed:
1. send (asynchronous) metadata requests
2. poll for metadata responses *indefinitely until we get it*
2. if there is fetch data available, **return it immediately**
3. if there is no fetch request in flight, send fetch requests
4. poll for fetch responses (counts against timeout)
- if no response within timeout, **return an empty collection** (leaving async fetch request for the next poll)
- if we get a response, **return the response**
One notable usage is prohibited by the new `poll`: previously, you could call `poll(0)` to block for metadata updates, for example to initialize the client, supposedly without fetching records. Note, though, that this behavior is not according to any contract, and there is no guarantee that `poll(0)` won't return records the first time it's called. Therefore, it has always been unsafe to ignore the response.
Little back story on this. Was helping a user over email. This could be much easier to debug if we assume that the connector developer might not return valid configs. For example Intellij will generate a stub that returns a null. This was the case that inspired this JIRA.
Author: Jeremy Custenborder <jcustenborder@gmail.com>
Reviewers: Jason Gustafson <jason@confluent.io>, Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#3762 from jcustenborder/KAFKA-5807
We no longer need them since we now require Java 8.
Author: Ismael Juma <ismael@juma.me.uk>
Reviewers: Andras Beni <andrasbeni@cloudera.com>, Manikumar Reddy O <manikumar.reddy@gmail.com>, Dong Lin <lindong28@gmail.com>
Closes#5049 from ijuma/remove-base64
* Set --source, --target and --release to 1.8.
* Build Scala 2.12 by default.
* Remove some conditionals in the build file now that Java 8
is the minimum version.
* Bump the version of Jetty, Jersey and Checkstyle (the newer
versions require Java 8).
* Fixed issues uncovered by the new version if Checkstyle.
* A couple of minor updates to handle an incompatible source
change in the new version of Jetty.
* Add dependency to jersey-hk2 to fix failing tests caused
by Jersey upgrade.
* Update release script to use Java 8 and to take into account
that Scala 2.12 is now built by default.
* While we're at it, bump the version of Gradle, Gradle plugins,
ScalaLogging, JMH and apache directory api.
* Minor documentation updates including the readme and upgrade
notes. A number of Streams Java 7 examples can be removed
subsequently.
Jason Gustafson
Ron Dagostino
jonathanskrzypek
Edoardo Comar
Ismael Juma
Konstantine Karantasis
Robert Yokota
Kevin Lu
Amit Sela
Michał Borowiecki
Randall Hauch
Kevin Lafferty
Maciej Bryński
Koen De Groote
Viktor Somogyi
Arjun Satish
Yu Yang
Chia-Ping Tsai
Gunnar Morling
Magesh Nandakumar
Chris Egerton
John Roesler
Jeremy Custenborder