maven buildnumber plugin error The scm url cannot be null

I am a new user of Maven, and am having difficulty getting the buildnumber-maven-plugin to do what I expect. Essentially, I want maven to build my project and create a JAR file of the result, and to set a build number in the manifest.mf file. I'll include most of my pom.xml file below. I've posted a related question already, but this question is about a different problem!

When I run mvn clean compile package I see the following error:

[ERROR] Failed to execute goal org.codehaus.mojo:buildnumber-maven-plugin:1.4:create (buildnumber) on project xcase: Execution buildnumber of goal org.codehaus.mojo:buildnumber-maven-plugin:1.4:create failed: The scm url cannot be null. -> [Help 1]

I have set both doCheck and doUpdate to false, so don't know why the SCM is involved. My workaround has been to add some dummy SCM configuration, but this feels clunky. Is there a better way?

  <scm>
    <connection>scm:svn:http://127.0.0.1/dummy</connection>
    <developerConnection>scm:svn:https://127.0.0.1/dummy</developerConnection>
    <tag>HEAD</tag>
    <url>http://127.0.0.1/dummy</url>
  </scm>

Here is the build section of my pom.xml file:

  <build>
    <outputDirectory>build</outputDirectory>
    <plugins>
      <plugin>
        <artifactId>buildnumber-maven-plugin</artifactId>
        <configuration>
          <buildNumberPropertyName>buildNumber</buildNumberPropertyName>
          <doCheck>false</doCheck>
          <doUpdate>false</doUpdate>
          <format>{0,number,integer}</format>
          <items>
            <item>buildNumber</item>
          </items>
          <revisionOnScmFailure>true</revisionOnScmFailure>
        </configuration>
        <executions>
          <execution>
            <goals>
              <goal>create</goal>
            </goals>
            <id>buildnumber</id>
          </execution>
        </executions>
        <groupId>org.codehaus.mojo</groupId>
        <version>1.4</version>
      </plugin>
      <plugin>
        <artifactId>maven-resources-plugin</artifactId>
        <version>3.0.2</version>
        <executions>
          <execution>
            <id>copy-resources</id>
            <phase>validate</phase>
            <goals>
              <goal>copy-resources</goal>
            </goals>
            <configuration>
              <outputDirectory>${basedir}/build</outputDirectory>
              <resources>          
                <resource>
                  <directory>${basedir}</directory>
                  <filtering>true</filtering>
                  <excludes>
                    <exclude>*local*.properties</exclude>
                  </excludes>
                  <includes>
                    <include>*.properties</include>
                  </includes>
                </resource>
                <resource>
                  <directory>${basedir}/src/java</directory>
                  <filtering>true</filtering>
                  <includes>
                    <include>log4j2.xml</include>
                  </includes>
                </resource>
              </resources>              
            </configuration>            
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <version>2.1</version>
        <configuration>
          <archive>
            <manifest>
              <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
            </manifest>
            <manifestEntries>
              <Implementation-Build>${buildNumber}</Implementation-Build>
            </manifestEntries>
          </archive>
        </configuration>
      </plugin>
    </plugins>
    <sourceDirectory>src/java</sourceDirectory>
  </build>