Report Builder, or "new style reports", replacing legacy reports (in reportdesign). Started as an extension called "Sun Report Builder" then "Oracle Report Builder" https://extensions.openoffice.org/project/reportdesign, which got bundled with LibreOffice, then converted to an optionally installable (but installed by default) part of LibreOffice proper.
Uses the Pentaho Reporting Flow Engine of Pentaho BI http://www.pentaho.com/.