Add content that prevents page breaks inside

Question

Using docx4j I'm adding multiple dynamically filled subTemplates to my main template.
I don't want to have page breaks inside those subTemplates (unless even a whole page is too small for one).
Therefore: If a subTemplate would break inside, I want to move the whole subTemplate to the next page.
How do I do this?

My code so far:

//... 
WordprocessingMLPackage mainTemplate = getWp();//ignore this method
List<WordprocessingMLPackage> projectTemplates = new ArrayList<>();

List<Project> projects = getProjects();//ignore this method
for (Project project : projects) {
  WordprocessingMLPackage template = getWpProject();//ignore this method
  //fill template with content from project
  //...
  projectList.add(template);
}

//Here's the part that will have to be changed I think:
//Since the projectTemplate only consists of tables I just added all its tables to the main template 
for (WordprocessingMLPackage temp : projectTemplates){
  List<Object> tables = doc.getAllElementFromObject(temp.getMainDocumentPart(), Tbl.class);
  for (Object table : tables) {
    mainTemplate.getMainDocumentPart().addObject(table);
  }
}

If you can think of a way to change the .docx template with Word to achieve my goal feel free to suggest it.
And if you have suggestions for code improvement in general just write a comment.

Answer 1

I made this "workaround" that works nicely for me:
I count all rows together and also check if the text inside the rows breaks (with an approximate threshold).
Then I add the rows of each project up and as soon as there are too many rows I insert a break before the current project and start over.

final int maxRowCountPerPage = 44;
final int maxLettersPerLineInDescr = 55;
int totalRowCount = 0;

WordprocessingMLPackage mainTemplate = getWp();

//Iterate over projects
for (Project project : getProjects()) {
  WordprocessingMLPackage template = this.getWpProject();
  String projectDescription = project.getDescr();

  //Fill template...

  //Count the lines
  int rowsInProjectDescr = (int) Math.floor((double) projectDescription.length() / maxLettersPerLineInDescr);
  int projectRowCount = 0;
  List<Object> tables = doc.getAllElementFromObject(template.getMainDocumentPart(), Tbl.class);
  for (Object table : tables) {
    List<Object> rows = doc.getAllElementFromObject(table, Tr.class);
    int tableRowCount = rows.size();
    projectRowCount += tableRowCount;
  }
  //System.out.println("projectRowCount before desc:" + projectRowCount);
  projectRowCount += rowsInProjectDescr;
  //System.out.println("projectRowCount after desc:" + projectRowCount);
  totalRowCount += projectRowCount;
  //System.out.println("totalRowCount: " + totalRowCount);

  //Break page if too many lines for page
  if (totalRowCount > maxRowCountPerPage) {
    addPageBreak(wp);
    totalRowCount = projectRowCount;
  }
  //Add project template to main template
  for (Object table : tables) {
    mainTemplate.getMainDocumentPart().addObject(table);
  }
}

If you notice a way to make the code nicer, let me know in a comment!