<plugin><!-- Copy Dependencies - NonMaven Jars -->
  <artifactId>maven-resources-plugin</artifactId>
  <version>2.5</version>
  <executions>
    <execution>
      <id>copy-resources</id>
      <phase>generate-resources</phase>
      <goals>
        <goal>copy-resources</goal>
      </goals>
      <configuration>
        <encoding>UTF-8</encoding>
        <outputDirectory>target/lib</outputDirectory>
        <resources>
          <resource>
            <directory>lib</directory>
            <filtering>false</filtering>
          </resource>
        </resources>
      </configuration>
    </execution>
  </executions>
</plugin>

If filtering is set to true, Maven will parse the file using the encoding and rewrite it, I have found that his can cause all sorts of issues including class not found errors.