feat: upgrade okhttp3 dependency to 3.14.9

BREAKING CHANGE: With this change, we're removing support for Java 7.

Note: this commit is a re-introduction of commit
f4c97b0 with a new commit message

.travis.yml

@@ -1,8 +1,7 @@
 language: java
 dist: trusty
 jdk:
-- openjdk7
-- oraclejdk8
+- openjdk8
 
 notifications:
   email: true
@@ -58,15 +57,15 @@ deploy:
   skip_cleanup: true
   on:
     branch: master
-    jdk: openjdk7
+    jdk: openjdk8
 - provider: bintray
   file: bintray-config.json
   user: $BINTRAY_USER
   key:  $BINTRAY_APIKEY
   skip_cleanup: true
   on:
     tags: true
-    jdk: openjdk7
+    jdk: openjdk8
 - provider: releases
   api_key: $GH_TOKEN
   file_glob: true
@@ -75,13 +74,13 @@ deploy:
   skip_cleanup: true
   on:
     tags: true
-    jdk: openjdk7
+    jdk: openjdk8
 - provider: script
   script: "./build/push-javadoc-to-gh-pages.sh"
   skip_cleanup: true
   on:
     tags: true
-    jdk: openjdk7
+    jdk: openjdk8
 
 # Ask bintray to sync the just-deployed artifact to maven central
 after_script:

README.md

@@ -28,7 +28,7 @@ You can use this project by defining it as a dependency within your Java SDK pro
 ```
 
 ## Prerequisites
-- Java SE version 7 or newer is required
+- Java SE version 8 or newer is required
 
 ## Javadoc
 You can find the Javadoc for this project here: https://ibm.github.io/java-sdk-core/

pom.xml

@@ -40,7 +40,7 @@
         <checkstyle-plugin-version>3.0.0</checkstyle-plugin-version>
         <jacoco-plugin-version>0.8.3</jacoco-plugin-version>
         <compiler-plugin-version>3.8.0</compiler-plugin-version>
-        <okhttp3-version>3.12.1</okhttp3-version>
+        <okhttp3-version>3.14.9</okhttp3-version>
         <logback-version>1.2.3</logback-version>
         <guava-version>27.1-android</guava-version>
         <gson-version>2.8.5</gson-version>