I have list hierarchy object, which can have list of grouping object each having single parent and multiple child values to parent_value object.Input from java object looks like below:

<hierarchy>
    <grouping>
        <parent_value>
            <value>3825709035</value>
            <display>Car</display>
        </parent_value>
        <child_value>
            <value>3825709039</value>
            <display>Baleno</display>
        </child_value>
        <child_value>
            <value>3825709051</value>
            <display>I20</display>
        </child_value>
    </grouping>
    <grouping>
        <parent_value>
            <value>3825709011</value>
            <display>Vehicle</display>
        </parent_value>
        <child_value>
            <value>3825709027</value>
            <display>Bus</display>
        </child_value>
        <child_value>
            <value>3825709015</value>
            <display>Bike</display>
        </child_value>
        <child_value>
            <value>3825709015</value>
            <display>Car</display>
        </child_value>
    </grouping>
</hierarchy>

I want output something like this, after iterating first grouping list, I want Car parent having Baleno and I20 if that was the only object in that list.

 Car
    Baleno
    I20

but after reading second grouping, since Vehicle also has Car as child, child should not come as separate section instead come under Vehicle parent. My final output should not come like this

 Car
    Baleno
    I20
 Vehicle
    Bus
    Bike
    Car
       Baleno
       I20

instead final output should be like below:

Vehicle
    Bus
    Bike
    Car
       Baleno
       I20

How to we come up with logic in java where we can iterate each grouping and have track of each child and its parent so that if we have parent as child of another parent then it should come in child section and not as parent assuming we have

List groups = hierarchy.getGroups();
and Grouping object has common object CommonHelper since same value and display exists for both parent_value and child_value.Grouping class will have

class Grouping
{
   CommonHelper parent_value;
   List<CommonHelper> child_value;
}

class CommonHelper
{
   long value;
   String display;
}