Bad request errors from Sonatype's Nexus during release

So we changed the way we published our artifacts to the repository - going straight to the Nexus, instead of via Apache and having Nexus index them. This meant it was easier from a permissions perspective - making sure the right people could upload artifacts into the right places and Nexus and Apache kept mixing up on-disk file permissions.

That unfortunately turned up a very annoying bug in Nexus - you can't attach 0 length files. Typically for artifacts that could generate a WSDL from code, we'd attach them as a -wsdl classifier artifact into the repository. If there were none, then we would touch the file, so the build-helper plugin could be configured to attach the file, otherwise it would fail.

But the move to Nexus knocked that on the head and we could no longer release web service artifacts - so if you run into a situation when you are releasing artifacts and you get a bad request for no good reason - it may be because you are trying to upload a zero length artifact.

The fix was to remove the zero length file and upgrade to 1.6 of the build helper plugin which has a new capability to skip the attachment if its empty. Our plugin definition now looks something like this:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <version>1.6</version>
    <executions>
     <execution>
      <id>attach-artifacts</id>
      <phase>package</phase>
      <goals>
       <goal>attach-artifact</goal>
      </goals>
      <configuration>
       <skipAttach>true</skipAttach> <!-- if the file doesn't exist, skip attaching it, added since 1.6 -->
       <artifacts>
        <artifact>
         <file>${project.build.directory}/generated-wsdl.jar</file>
         <type>jar</type>
         <classifier>wsdl</classifier>
        </artifact>
       </artifacts>
      </configuration>
     </execution>
    </executions>
   </plugin>