[gax-java] fix: make GaxProperties.version accessible in Android

.gitignore

@@ -16,3 +16,6 @@ bazel-*
 # IntelliJ
 .idea
 out
+
+# Auto-generated files.
+gax/src/main/resources/dependencies.properties

build.gradle

@@ -40,6 +40,15 @@ googleJavaFormat {
   exclude 'build/**'
   exclude 'bazel*/**'
 }
+
+task generateProjectProperties {
+    ext.outputFile = file("gax/src/main/resources/dependencies.properties")
+    outputs.file(outputFile)
+    doLast {
+        outputFile.text = "version.gax=${project.version}"
+    }
+}
+
 // google-java-format-gradle-plugin:0.8 does not work with Java 1.7.
 verifyGoogleJavaFormat.onlyIf { JavaVersion.current().isJava8Compatible() }
 
@@ -84,6 +93,7 @@ allprojects {
     }
   }
   test.dependsOn verifyLicense
+  test.dependsOn generateProjectProperties
 
   gradle.projectsEvaluated {
     tasks.withType(JavaCompile) {
@@ -159,13 +169,15 @@ subprojects {
 
   check.dependsOn jacocoTestReport
 
+
   // Source jar
   // ----------
 
   task sourcesJar(type: Jar, dependsOn: classes) {
+    dependsOn generateProjectProperties
     classifier = 'sources'
-    from sourceSets.main.allSource, sourceSets.test.allSource
 
+    from sourceSets.main.allSource, sourceSets.test.allSource, sourceSets.main.resources.srcDirs
     exclude('**/*Test.java')
   }
 

gax/src/main/java/com/google/api/gax/core/GaxProperties.java

@@ -57,9 +57,13 @@ public static String getLibraryVersion(Class<?> libraryClass) {
    * method are expected to be cached.
    */
   public static String getLibraryVersion(Class<?> libraryClass, String propertyName) {
-    String version = getLibraryVersion(libraryClass);
-    if (!DEFAULT_VERSION.equals(version)) {
-      return version;
+    String version = null;
+    // Always read GaxProperties' version from the properties file.
+    if (!libraryClass.equals(GaxProperties.class)) {
+      version = getLibraryVersion(libraryClass);
+      if (!DEFAULT_VERSION.equals(version)) {
+        return version;
+      }
     }
 
     try (InputStream in = libraryClass.getResourceAsStream("/dependencies.properties")) {

gax/src/test/java/com/google/api/gax/core/GaxPropertiesTest.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google LLC nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.google.api.gax.core;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.regex.Pattern;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class GaxPropertiesTest {
+
+  @Test
+  public void testGaxVersion() {
+    String gaxVersion = GaxProperties.getGaxVersion();
+    assertTrue(Pattern.compile("^\\d+\\.\\d+\\.\\d+").matcher(gaxVersion).find());
+    String[] versionComponents = gaxVersion.split("\\.");
+    // This test was added in version 1.56.0, so check that the major and minor numbers are greater
+    // than that.
+    int major = Integer.parseInt(versionComponents[0]);
+    int minor = Integer.parseInt(versionComponents[1]);
+
+    assertTrue(major >= 1);
+    if (major == 1) {
+      assertTrue(minor >= 56);
+    }
+  }
+}