chore: consolidate build configuration to parent

[meltsufin]

Moving this block from jar modules to jar-parent.

  <build>
    <plugins>
      <plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>flatten-maven-plugin</artifactId>
        </plugin>
    </plugins>
  </build>

Removing this block from module parents. Since dependencies.sh is not run at all, it's not clear if these exclusions are still needed.

  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-dependency-plugin</artifactId>
          <configuration>
            <ignoredUnusedDeclaredDependencies>
              <ignoredUnusedDeclaredDependency>org.objenesis:objenesis</ignoredUnusedDeclaredDependency>
              <ignoredUnusedDeclaredDependency>javax.annotation:javax.annotation-api</ignoredUnusedDeclaredDependency>
            </ignoredUnusedDeclaredDependencies>
          </configuration>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>

Removing javax.annotation declaration for Java 9+, since the dependency is already present transitively through api-common.

  <profiles>
    <profile>
      <id>java9</id>
      <activation>
        <jdk>[9,)</jdk>
      </activation>
      <dependencies>
        <dependency>
          <groupId>javax.annotation</groupId>
          <artifactId>javax.annotation-api</artifactId>
        </dependency>
      </dependencies>
    </profile>
  </profiles>

[suztomo]

Removing javax.annotation declaration for Java 9+, since the dependency is already present transitively through api-common.

It's a good practice to declare the dependency if a project touches a class from it, without relying on transitive dependencies ("Undeclared but used"). Can you move the javax.annotation part to google-cloud-jar-parent?

[meltsufin]

Removing javax.annotation declaration for Java 9+, since the dependency is already present transitively through api-common.

It's a good practice to declare the dependency if a project touches a class from it, without relying on transitive dependencies ("Undeclared but used"). Can you move the javax.annotation part to google-cloud-jar-parent?

Since we flatten the poms, I guess it will be declared. Declaring and not using a dependency is also a bad practice. So, I'm torn on this one.

[suztomo]

Since we flatten the poms, I guess it will be declared.

That's correct, it will be declared anyway. However, skipping dependency declaration (for the flatten plugin's effect) means we can/should remove lots of other dependencies as well. The reasoning would become complex. For example, you had to reason "javax-annotation dependency is already present transitively through api-common". I don't want people spending time on such dependency analysis to decide whether a dependency should be declared. Therefore, I think we should reason about dependency declaration without considering the effect of the flatten plugin.

[suztomo]

Nice survey.

suztomo@suztomo2:~/google-cloud-java$ grep -ir 'import javax.annotation' . |grep -v Generated
./README.md:import javax.annotation.Nullable;
suztomo@suztomo2:~/google-cloud-java$