* chore:add javadoc about being called within single thread

* rephrased the words

* Updated with feedback comment

* removed extra whitespace

Fixes #870

* fix: scale number of threads to scale with number of cpus

This is temporary solution until something better can be worked out.
Ideally we would separate the executor for gax and the transport provider. But there are some backwards compatibility concerns to workout first.

* use numCpus

* Google-java-format-plugin 0.8

* Applied google-java-format with new version

* VerifyGoogleJavaFormat only for Java8

* onlyIf

* isJava8Compatible

* Added comment

* empty commit for Kokoro build

* Jacoco 0.8.2

* Giving up Jacoco upgrade

* What went wrong:
A problem occurred configuring root project 'gax-java'.
> Could not resolve all artifacts for configuration ':classpath'.
   > Could not resolve gradle.plugin.com.dorongold.plugins:task-tree:1.3.1.
     Required by:
         project :
      > Could not resolve gradle.plugin.com.dorongold.plugins:task-tree:1.3.1.
         > Could not get resource 'https://plugins.gradle.org/m2/gradle/plugin/com/dorongold/plugins/task-tree/1.3.1/task-tree-1.3.1.pom'.
            > Could not GET 'https://plugins.gradle.org/m2/gradle/plugin/com/dorongold/plugins/task-tree/1.3.1/task-tree-1.3.1.pom'.
               > sun.security.validator.ValidatorException: PKIX path validation failed: java.security.cert.CertPathValidatorException: signature check failed

https://source.cloud.google.com/results/invocations/e8c74bc9-fc2d-4047-82b8-3e2d5b9cdc64/targets/cloud-devrel%2Fclient-libraries%2Fjava%2Fgax-java%2Fpresubmit%2Fjava7/log

* Setting up linkage monitor Kokoro build config

* 2020

* Gradle install

* Comment

* Revert testing

* No need to sign the JAR

* revert gradle

* dep: update protobuf and gRPC

@chingor13 fixes #845

* remove java format plugin that's not compatible with java 11

* fix merge conflict

Co-authored-by: Jeff Ching <chingor@google.com>