title: Gradle copy task isn't overwriting file
body: <p>I've got the following task:</p>
  
  <p>preBuild.dependsOn "copyConfigFile"</p>
  
  <pre><code>task copyConfigFile(type: Copy) {
          from 'ConfigSources/VersionInfo.java'
          into 'src/main/java/com/company/gradleexperiments/'
  
          expand([changeset: "12345",
                  changeset_time: "the time",
                  changeset_date  : "the date"])
  }
  </code></pre>
  
  <p>Its works as expected except after the file has been initially copied, if I change one of the values in the expand and build again, then the file is not being overwritten (the creation timestamp of the file in the target destination remains that last time it was built).</p>
  
  <p>I did some googling and searching of past questions on this topic, however the answer I got was that the gradle copy task is by default always supposed to overwrite the file. If that is the case, then why is it not doing so for me?</p>