Migrate from Travis CI to GitHub Actions (#158)

While there, drop the now-obsolete Takari Maven plugin.

.github/workflows/build.yaml

@@ -0,0 +1,37 @@
+name: Build and verify
+on:
+  pull_request:
+  push:
+    branches:
+      - 'master'
+jobs:
+  build:
+    runs-on: ubuntu-22.04
+    strategy:
+      matrix:
+        jdk: [ 11.0.16, 17.0.4 ]
+    steps:
+        # We run the build twice for each supported JDK: once against the
+        # original Error Prone release, using only Error Prone checks available
+        # on Maven Central, and once against the Picnic Error Prone fork,
+        # additionally enabling all checks defined in this project and any
+        # Error Prone checks available only from other artifact repositories.
+      - name: Check out code
+        uses: actions/checkout@v3.0.2
+      - name: Set up JDK
+        uses: actions/setup-java@v3.4.1
+        with:
+          java-version: ${{ matrix.jdk }}
+          distribution: temurin
+          cache: maven
+      - name: Display build environment details
+        run: mvn --version
+      - name: Build project against vanilla Error Prone
+        run: mvn -T1C install
+      - name: Build project with self-check against Error Prone fork
+        run: mvn -T1C clean verify -Perror-prone-fork -Pnon-maven-central -Pself-check -s settings.xml
+      - name: Remove installed project artifacts
+        run: mvn build-helper:remove-project-artifact
+
+# XXX: Enable Codecov once we "go public".
+# XXX: Enable SonarCloud once we "go public".

.mvn/maven.config

@@ -0,0 +1 @@
+--batch-mode --errors --strict-checksums

.travis.yml

@@ -1,38 +0,0 @@
----
-dist: bionic
-language: java
-jdk: openjdk11
-addons:
-  sonarcloud:
-    organization: picnic-technologies
-    token: "${SONARCLOUD_TOKEN}"
-install:
-  - mvn io.takari:maven:wrapper
-script:
-  # We run the build twice: once against the original Error Prone release,
-  # using only Error Prone checks available on Maven Central, and once against
-  # the Picnic Error Prone fork, additionally enabling all checks defined in
-  # this project and any Error Prone checks available only from other artifact
-  # repositories.
-  - ./mvnw clean install
-  - ./mvnw clean install -Perror-prone-fork -Pnon-maven-central -Pself-check -s settings.xml
-  # XXX: Enable SonarCloud once we "go public".
-  # ./mvnw jacoco:prepare-agent surefire:test jacoco:report sonar:sonar
-  - ./mvnw jacoco:prepare-agent surefire:test jacoco:report
-before_cache:
-  # Don't cache the artifacts we just generated, for multiple reasons: (1) we
-  # shouldn't need them next time around and (2) if we do, that indicates a
-  # dependency issue which might otherwise go unnoticed until next time we bump
-  # the project's version (i.e., when tagging).
-  - find "${HOME}/.m2/repository" -depth -name '*-SNAPSHOT' -exec rm -r '{}' \;
-cache:
-  directories:
-    # The local Maven repository in which third party dependencies are stored.
-    - ${HOME}/.m2/repository
-    # The Takari Maven Wrapper's storage for downloaded Maven distributions.
-    - ${HOME}/.m2/wrapper
-    # The SonarQube analysis cache.
-    - ${HOME}/.sonar/cache
-# XXX: Enable Codecov once we "go public".
-#after_success:
-#  - bash <(curl -s https://codecov.io/bash)

pom.xml

@@ -140,6 +140,7 @@
         <version.findbugs-format-string>3.0.0</version.findbugs-format-string>
         <version.guava-beta-checker>1.0</version.guava-beta-checker>
         <version.jdk>11</version.jdk>
+        <!-- XXX: Configure Renovate to open upgrade PRs for this property. -->
         <version.maven>3.6.3</version.maven>
         <version.mockito>4.6.1</version.mockito>
         <version.nopen-checker>1.0.1</version.nopen-checker>
@@ -488,14 +489,6 @@
                         </execution>
                     </executions>
                 </plugin>
-                <plugin>
-                    <groupId>io.takari</groupId>
-                    <artifactId>maven</artifactId>
-                    <version>0.7.7</version>
-                    <configuration>
-                        <maven>${version.maven}</maven>
-                    </configuration>
-                </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-checkstyle-plugin</artifactId>
@@ -1046,6 +1039,11 @@
                         </dependency>
                     </dependencies>
                 </plugin>
+                <plugin>
+                    <groupId>org.codehaus.mojo</groupId>
+                    <artifactId>build-helper-maven-plugin</artifactId>
+                    <version>3.3.0</version>
+                </plugin>
                 <plugin>
                     <groupId>org.codehaus.mojo</groupId>
                     <artifactId>buildnumber-maven-plugin</artifactId>