Use a special flag to indicate hidden children of a field.

Added new method in PdmUiItem called isUiHideChildren()
p4#: 22093

ApplicationCode/ProjectDataModel/RimResultSlot.cpp

@@ -49,6 +49,7 @@ RimResultSlot::RimResultSlot()
     CAF_PDM_InitFieldNoDefault(&legendConfig, "LegendDefinition", "Legend Definition", "", "", "");
     CAF_PDM_InitFieldNoDefault(&m_legendConfigData, "ResultVarLegendDefinitionList", "", "", "", "");
     m_legendConfigData.setUiHidden(true);
+    m_legendConfigData.setUiHideChildren(true);
 
     legendConfig = new RimLegendConfig();
 }