setting active profile defined in parent pom in project pom - maven

Question

We have a corporate wide Super Pom we use to define many of the defaults we use. For example, the Super Pom defines what version of the JDK to use, and other parameters. This is inherited by our projects as the parent pom.
Most of our projects use JDK 1.7, but one set of projects is still on version JDK 1.6. I've put the following profile definitions in my parent pom:
<properties>
<travelclick.snapshot.repo>artifactory/libs-snapshot-local</travelclick.snapshot.repo>
<old.javac.source>1.5</old.javac.source>
<old.javac.target>1.6</old.javac.target>
</properties>
<profiles>
...
<profile>
<id>jdk1.6</id>
<build>
<plugins>
<plugin>
<groupId>com.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<configuration>
<...>
<source>${old.javac.source}</source>
<target>${old.javac.target}</target>
<...>
</configuration>
</plugin>
</plugins>
</build>
</profile>
<...>
</profiles>
Now, I have a profile called jdk1.6 and I'd like to specify in the project's pom that it should use this one by default. How do I do this?
I've tried adding into the project's pom:
<profiles>
<profile>
<id>jdk1.6</id>
<activations>
<activeByDefault>true</activeByDefault>
</activations>
</profile>
</profile>
But that redefines my jdk1.6 profile.
I've tried putting in this:
<activeProfiles>
<activeProfile>jdk1.6</activeProfile>
</activeProfiles>
But that only works in settings.xml.
How do I specify a profile in the parent pom, and then say that this is the active profile in the child pom?
More Attempts
I've tried using properties. In my parent pom.xml:
<profiles>
<profile>
<id>jdk1.6</id>
<activation>
<property>
<name>use-jdk1.6</name>
</property>
</activation>
<profile>
</profiles>
And the following in my local pom:
<properties>
<use-jdk1.6>true</use-jdk1.6>
</properties>
But, it doesn't pick up the profile. And, this does work:
$ mvn -Puse-jdk1.6 clean package site
So, I know that the parent profiles do work.
Profiles
Could you add yours profile details exectuing goal help:all-profiles
[INFO] Listing Profiles for Project: xxxx
Profile Id: artifactory (Active: true , Source: settings.xml)
Profile Id: jdk1.6 (Active: false , Source: pom)
Profile Id: arse-version (Active: false , Source: pom)
Profile Id: urge (Active: false , Source: pom)
I can activate jdk1.6 from the command line. I just want to activate it as the default in my child poms.

Answer 1

AAAAHGGGGHHHH!
That's me screaming.
I found the issue and why this wasn't working.
In my parent pom, I had the following:
<properties>
<javac.source>1.7</javac.source>
<javac.source>1.7</javac.source>
<old.javac.source>1.7</old.javac.source>
<old.javac.source>1.7</old.javac.source>
...
</properties>
<profiles>
<profile>
<id>jdk1.6</id>
<activation>
<property>
<name>use-jdk1.6</name>
</property>
</activation>
<build>
<plugins>
....
<plugin>
<groupId>maven-compiler-plugin</groupId>
...
<configuration>
<!-- This isn't doing what I think -->
<source>${old.javac.source}</source>
<target>${old.javac.target}</source>
...
</configuration>
</plugin>
</plugins>
<profile>
In my child pom, I had this:
<properties>
<use-jdk1.6>true</use-jdk1.6>
</properties>
And, it appeared that setting the use-jdk1.6 property just wasn't working. However, that wasn't the case. I was setting the profile.
What happens is if I have the system property javac.source and javac.target set, it overrides the configuration of the maven-compiler-pluing (even though I had explicitly set <source> and <target> not to use version 1.7).
So, I spent six hours on this issue before I realized it was due to me setting a property named javac.source rather than something like java-version.