I've been investigating how to automate the compilation with maven when using both annotation processors, lombok & cofoja. I've found finally how to compile and run test without conflicts. Here I write the relevant pom fragment:
...
<dependency>
<groupId>com.google.java.contract</groupId>
<artifactId>cofoja</artifactId>
<version>1.1-r150</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.12.6</version>
</dependency>
...
<build>
<plugins>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<id>copy-agents</id>
<phase>initialize</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<artifactItems>
<artifactItem>
<groupId>com.google.java.contract</groupId>
<artifactId>cofoja</artifactId>
<version>1.1-r150</version>
<outputDirectory>${project.build.directory}/agents</outputDirectory>
<destFileName>cofoja-1.1-r150.jar</destFileName>
</artifactItem>
<artifactItem>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.12.6</version>
<outputDirectory>${project.build.directory}/agents</outputDirectory>
<destFileName>lombok-1.12.6.jar</destFileName>
</artifactItem>
</artifactItems>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
<executions>
<execution>
<id>default-compile></id>
<configuration>
<includes>
<include>${project.build.directory}/agents/lombok-1.12.6.jar</include>
</includes>
</configuration>
</execution>
<execution>
<id>compile-everything-else</id>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
<configuration>
<compilerArgument>-proc:only</compilerArgument>
<includes>
<include>${project.build.directory}/agents/cofoja-1.1-r150.jar</include>
</includes>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.17</version>
<executions>
<execution>
<phase>test</phase>
</execution>
</executions>
<configuration>
<argLine>-javaagent:${project.build.directory}/agents/cofoja-1.1-r150.jar</argLine>
</configuration>
</plugin>
...