Skip blank and header lines in Maven-generated dependencies list

[waynebeaton]

When one uses the dependencies:list feature, the output includes some blank and header lines. For example:

The following files have been resolved:
   none


The following files have been resolved:
   p2.eclipse-plugin:com.google.gson:jar:2.8.6.v20201231-1626:system
...

These are identified by the tool as invalid content, but are still included in the output (and in the generated summary file):

License information could not be automatically verified for the following content:

Invalid:    none
Invalid: The following files have been resolved:
...

At very least these lines should just be ignored. Perhaps consider adding an option to ignore all invalid content.