For a simple copy-tasks I can recommend copy-rename-maven-plugin. It's straight forward and simple to use:
<project>
...
<build>
<plugins>
<plugin>
<groupId>com.coderplus.maven.plugins</groupId>
<artifactId>copy-rename-maven-plugin</artifactId>
<version>1.0</version>
<executions>
<execution>
<id>copy-file</id>
<phase>generate-sources</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<sourceFile>src/someDirectory/test.environment.properties</sourceFile>
<destinationFile>target/someDir/environment.properties</destinationFile>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
If you would like to copy more than one file, replace the <sourceFile>...</destinationFile>
part with
<fileSets>
<fileSet>
<sourceFile>src/someDirectory/test.environment.properties</sourceFile>
<destinationFile>target/someDir/environment.properties</destinationFile>
</fileSet>
<fileSet>
<sourceFile>src/someDirectory/test.logback.xml</sourceFile>
<destinationFile>target/someDir/logback.xml</destinationFile>
</fileSet>
</fileSets>
Furthermore you can specify multiple executions in multiple phases if needed, the second goal is "rename", which simply does what it says while the rest of the configuration stays the same. For more usage examples refer to the Usage-Page.
Note: This plugin can only copy files, not directories. (Thanks to @james.garriss for finding this limitation.)