I'm re-opening this bug because there was an error in the example text.
Usually, abbrevations do end with a dot. And the directly following word
after this abbrevation can start with a lowercase letter.
JLanguageTool doesn't detect this if the abbrevation is located at
sentence's start. Following German example shows the problem. The
abbrevation, "ca.", is at sentence start and the following word, "alle", is
marked as wrong, but it isn't at sentence start:
Diese werden etc. eingefügt. Etc. und so weiter. Ca. alle Leute.