Update gradle and implement new dependency building

.gitignore

@@ -2,4 +2,5 @@ build/**
 .gradle/**
 out/**
 .idea/**
-.composite-enable
+.composite-enable
+gradle.properties

.travis.yml

@@ -12,19 +12,16 @@ cache:
 stages:
 - name: test
 - name: build
-- name: snapshot
-  if: branch = master
 - name: release
   if: branch = release
+before_script:
+  git checkout ${TRAVIS_BRANCH} # to fix issue with Grgit if travis checks out HEAD
 jobs:
   include:
   - stage: test
-    script: "./gradlew test"
+    script: "./gradlew test -PcheckoutIfCloned=true"
   - stage: build
-    script: "./gradlew build -x test"
-  - stage: snapshot
-    script: "./gradlew publish -x test -Dnexus.user=$NEXUS_USER -Dnexus.key=$NEXUS_KEY
-      -Dbuild.number=$TRAVIS_BUILD_NUMBER"
+    script: "./gradlew build -x test -PcheckoutIfCloned=true"
   - stage: release
     script: "./gradlew publish -x test -Ddisablesnapshot=true -Dnexus.user=$NEXUS_USER -Dnexus.key=$NEXUS_KEY
       -Dbuild.number=$TRAVIS_BUILD_NUMBER"

GRADLE_BUILD.md

@@ -0,0 +1,32 @@
+# Composite Build
+The **upb.crypto** libraries, except for **math** all depend on at least one of the other libraries.
+Often times, when developing for example **craco**, you might also be doing some changes to **math**.
+To include these changes faster, we make extensive use of Gradle`s [composite build](https://docs.gradle.org/current/userguide/composite_builds.html) feature.
+To make this easier to use, we have a composite build script contained in ``settings.gradle`` that decides when to enable composite builds and when not.
+It also serves to enable composite builds on the Travis CI.
+
+## Default Script Behaviour
+By default, the script will automatically clone **upb.crypto** dependencies that are not stored in the local file system yet.
+It clones them to the same folder that the top-level folder of the library being built is contained in.
+Furthermore, it checks that the branch names match. 
+If the library is on branch ``branch1`` and a dependency is on ``branch2``, the script will complain and tell you to checkout out branch ``branch1`` in the dependency's git.
+If no such branch exists, the library will instead want to use the ``master`` branch.
+
+You can customize this behaviour via the properties detailed in the following section.
+
+## Customizing the Script via Properties
+The composite build script can be customized via the following properties. 
+The parameters can be set via the ``gradle.properties`` file or set via command line as detailed [here](https://docs.gradle.org/current/userguide/build_environment.html). 
+
+- ``useCurrentBranch``: If defined (any value), will cause the composite build to use the currently
+    checked out branch of the dependencies.
+- ``checkoutIfCloned``: If defined (any value), will automatically check out the corresponding
+    dependency branch (branch with same name) given that the dependency was freshly cloned.
+    Used by the Travis CI to automatically switch to the right dependency branch for the build.
+
+An example ``gradle.properties`` file:
+```
+useCurrentBranch=""
+```
+Here, ``useCurrentBranch`` is enabled by giving it an empty String value.
+

build.gradle

@@ -1,7 +1,6 @@
 plugins {
     // Apply the java-library plugin to add support for Java Library
     id 'java-library'
-    id 'maven'
     id 'maven-publish'
 }
 
@@ -62,8 +61,7 @@ test {
 
 //packaging tests
 task packageTests(type: Jar) {
-    classifier = 'tests'
-    baseName = project.name + '-test'
+    archiveClassifier = 'tests'
     from sourceSets.test.output+sourceSets.test.allSource
 }
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,5 @@
-#Mon Oct 29 17:01:07 CET 2018
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.4-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.9-all.zip