This directory contains third party code which has been slightly modified for Bigtable specific use cases. Classes are added as additional source files to their corresponding modules. Example from bigtable-beam-import's pom.xml below:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>3.0.0</version>
<executions>
<execution>
<id>add-source</id>
<phase>generate-sources</phase>
<goals>
<goal>add-source</goal>
</goals>
<configuration>
<sources>
<source>../../third_party/third_party_hbase_server/src/main/import/</source>
</sources>
</configuration>
</execution>
</executions>
</plugin>