Restore leniency when parsing nested elements

[marcphilipp]

Prior to e0140ba322c1fb02a9f43078290195c6ba882a66, elements with children and a name other than property were ignored. We have code that relies on this to declare additional configuration for the maven-surefire-plugin that is later read from the XppDom object. This commit restores the prior leniency for nested elements and ignores all elements with children that don't have both a name and a value child element.

[kwin]

@marcphilipp Any chance you can add a test case?

[cstamas]

Unsure this PR is needed, as @marcphilipp found a fix for this (using lifecycle participant, that extracts and rewrites plugin configurations). So please confirm Marc.

This PR should be "on hold", not to be merged.

[marcphilipp]

Indeed, I found a fix by "filtering" Xpp3Dom before passing it to the converter.