Gaps between subreports in DynamicReport

Question

I have implemented a Report with Jasper Dynamic Reports.

In the main report I have included in details some subreports.

  JasperReportBuilder report = DynamicReports.report();
  report.addDetail(subReport1);
  report.addDetail(subReport2);

In the produced PDF, between the subreports there is a vertical gap. Is there a way to reduce this space?