private void doCheckIn(List<DomainFile> domainFiles) {
		if (!checkRepositoryConnected()) {
			return;
		}
		List<DomainFile> checkedOut = new ArrayList<>();
		for (DomainFile domainFile : domainFiles) {
			if (domainFile.isCheckedOut() && domainFile.modifiedSinceCheckout()) {
				checkedOut.add(domainFile);
			}
		}

		if (checkedOut.isEmpty()) {
			Msg.showInfo(this, parent, "No Modified Files",
				"No checked-out and modified files in the given selection");
			return;
		}

		if (checkedOut.size() > 0) {
			checkIn(checkedOut);
		}
	}
Determines the list of modified, checked out files and then checks them in.
Ghidra/Framework/Project/src/main/java/ghidra/framework/main/projectdata/actions/VersionControlCheckInAction.java