Unofficially support older Java versions

[mches]

Unofficially support older Java versions. Maven 3.2.x supports Java 6, and Maven 3.1.x and earlier support Java 5. In the future, support for Java 5 will have to be removed to build with Java 9, if building with javac.

[mosabua]

I think this is actually the wrong property name and it will not work like this. The right one is takari.javaSourceVersion I think.

However keep in mind that in order to get the wrapper into project you would have to use a newer Java version since the takari-maven-plugin needs Java 1.7 ...

So this change (if fixed) would compile the wrapper with Java 1.5 bytecode .. but then to get it into place you would still have to use Java 1.7 for the project you want to use the wrapper with..

And then you can build that project with the wrapper using 1.5 after manually changing the version to an older Maven version...

Is this really what you are after?

[mches]

@mosabua Thank you, I've corrected the property name in the branch for this PR and confirmed that the Takari Lifecycle Plugin accepts the configuration.

Yes, I think it's acceptable that Java 1.7 or later is necessary to install the Maven Wrapper, since it's a one-time task outside of the build. Thanks for being thorough.