Mapping in Dataweave

I have to do XML to JSON mapping in dataweave. The request XML is:

<Root>
    <AccRoot>
        <FinRoot>
            <FinData>
                <SomeValue>Test</SomeValue>
            </FinData>
            <PassRoot>
                <PassData>
                    <PassData2>
                        <Leg>001</Leg>
                        <Data>Sample1</Data>
                        <Data2>Sample2</Data2>
                        <Data3>Sample3</Data3>
                    </PassData2>
                </PassData>
            </PassRoot>
                <PassData>
                    <PassData2>
                        <Leg>002</Leg>
                        <Data>Sample21</Data>
                        <Data2>Sample22</Data2>
                        <Data3>Sample23</Data3>
                    </PassData2>
                </PassData>
            <PassRoot>
                <PassData>
                    <PassData2>
                        <Leg>003</Leg>
                        <Data>Sample31</Data>
                        <Data2>Sample32</Data2>
                        <Data3>Sample33</Data3>
                    </PassData2>
                </PassData>
            </PassRoot>
            <PassRoot>
                <PassData>
                    <PassData2>
                        <Leg>004</Leg>
                        <Data>Sample41</Data>
                        <Data2>Sample42</Data2>
                        <Data3>Sample43</Data3>
                    </PassData2>
                </PassData>
            </PassRoot>
        </FinEntity>
    </PrimeEntity>
</Root>

Resulting JSON should be

Result: Sample1:Sample2:Sample3.Sample21:Sample22:Sample23.Sample31:Sample32:Sample33.Sample41:Sample42:Sample43

i.e. I have to join all the records in 'PassData2' with ':' and then i have to check if 'Leg' with value '+1' is present, if yes then i have to do the same for those elements and join them with '.'

     %dw 1.0
 %output application/json
 ---
 {
     Result: payload.AccRoot.FinRoot..PassData2 
         orderBy ($.Leg as :number) 
         reduce ((val, acc = []) -> 
             (acc ++ [val]) when acc == [] or acc[-1].Leg as :number + 1 == val.Leg as :number 
             otherwise acc
         )
         map ([$.Data, $.Data2, $.Data3] joinBy ':')
         joinBy '.'
 }

1. Selects all PassData2 nodes

2. Orders them by Leg (in case they're unordered)

3. Performs a reduce to ensure the only elements in the array are those with sequential values for Leg

4. Maps each element left to a concatenation of it's Data* nodes using : as the separator

5. Joins that final array using .