Fix API Diff Gradle task

Prior to this change, the Gradle API Diff task was failing due to a
missing class (a Guava class) during processing. This might be a
dependency that was previously brought by some other dependency.

This commit adds that dependency as a workaround, and improves the
Gradle API Diff task to only select relevant projects when running the
task (projects using the Java Plugin and the Maven Publish Plugin).

buildSrc/build.gradle

@@ -9,7 +9,7 @@ repositories {
 
 dependencies {
 	implementation "me.champeau.gradle:japicmp-gradle-plugin:0.2.8"
-
+	implementation "com.google.guava:guava:18.0" // required by japicmp-gradle-plugin
 }
 
 gradlePlugin {

buildSrc/src/main/java/org/springframework/build/api/ApiDiffPlugin.java

@@ -29,6 +29,7 @@ import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.plugins.JavaBasePlugin;
 import org.gradle.api.plugins.JavaPlugin;
+import org.gradle.api.publish.maven.plugins.MavenPublishPlugin;
 import org.gradle.api.tasks.TaskProvider;
 import org.gradle.jvm.tasks.Jar;
 
@@ -90,8 +91,7 @@ public class ApiDiffPlugin implements Plugin<Project> {
 
 	private boolean isProjectEligible(Project project) {
 		return project.getPlugins().hasPlugin(JavaPlugin.class)
-				&& !project.getName().equals("spring-core-coroutines")
-				&& !project.getName().equals("spring-framework-bom");
+				&& project.getPlugins().hasPlugin(MavenPublishPlugin.class);
 	}
 
 	private Configuration createBaselineConfiguration(String baselineVersion, Project project) {