JOLT Show If else - json

Question

I have a problem and I don't know how to solve it, I want to get data from "B" if it exists and if it doesn't exist then data from "A".
I've done it but it only works for B, could it be improved in my code?
Input with B:
`
{
"P": {
"A": {
"One": {
"Two": {
"Three": [
{
"ID": "123456",
"Some": {
"ID_1": "123456789",
"AAA": "aaa"
}
}
]
}
}
},
"B": {
"One": {
"Two": {
"Three": [
{
"ID": "654321",
"Some": {
"ID_1": "987654321",
"BBB": "bbb"
}
}
]
}
}
}
}
}
`
Input without B:
`
{
"P": {
"A": {
"One": {
"Two": {
"Three": [
{
"ID": "123456",
"Some": {
"ID_1": "123456789",
"AAA": "aaa"
}
}
]
}
}
}
}
}
`
JSON Spec:
`
[
{
"operation": "modify-default-beta",
"spec": {
"P": {
"B": {
"One": {
"Two": {
"Three": {
"*": {
"ID": "null"
}
}
}
}
}
}
}
},
{
"operation": "shift",
"spec": {
"P": {
"B": {
"One": {
"Two": {
"Three": {
"*": {
"ID": {
"null": {
"#(6,A.One.Two.Three.ID)": "Data.ID",
"#(6,A.One.Two.Three.Some.ID_1)": "Data.ID_1",
"#(6,A.One.Two.Three.Some.AAA)": "Data.AAA"
},
"*": {
"#(2,ID)": "Data.ID",
"#(2,Some.ID_1)": "Data.ID_1",
"#(2,Some.BBB)": "Data.BBB"
}
}
}
}
}
}
}
}
}
}
]
`
Output:
{
"Data" : {
"ID" : "654321",
"ID_1" : "987654321",
"BBB" : "bbb"
}
}