System tests should unset the environment variables, set its own environment variables and then run.

AFAIK, this can be done only by tricky methods, and we have to modify the modifiable member from the unmodifiable map the System.getEnv() returns. Seems like the member is called "m", but this is dependent on the library and might change depending on version, but this is to be done.

A better way of doing this, is we should set these variables in flume-env.sh and then start the flume agent from the java code. This will cause the agent to source flume-env.sh and pick up the values we put in.