I fixed the previously mentioned error by removing bellow piece of code from openmrs-module-orderentryui/omod/pom.xml
<plugin>
<groupId>de.saumya.mojo</groupId>
<artifactId>gem-maven-plugin</artifactId>
<extensions>true</extensions>
<executions>
<execution>
<goals>
<goal>exec</goal>
</goals>
<phase>generate-resources</phase>
</execution>
</executions>
<configuration>
<jrubyVersion>1.7.10</jrubyVersion>
<execArgs>${project.build.directory}/rubygems/bin/compass compile ${basedir}/src/main/compass</execArgs>
</configuration>
</plugin>