Can cdxgen generate a SBOM that treat the parent pom as a whole?

[scypf]

We have some Java Maven Applications and the file structure was like:
root
--submodule1
--src
--pom.xml (pom1, package type is jar jar)
--submodule2
--src
--pom.xml (pom2, package type is jar jar)
--submodule3
--src
--pom.xml (pom3, package type is jar jar)
--pom.xml (root-pom, , package type is pom pom)

What we want is generating a SBOM which not only include all dependencies in pom1, pom2, pom3 and root pom, but also take each pom file as a separate block inside so that we can use it to get the dependency tree in the next step. for example in bom.json:

[
{
"ref": "pkg:from pom 1",
"dependsOn": [
"pkg:maven/xxxx",
"pkg:maven/xxxxxx",
]
},
{
"ref": "pkg:from pom 2",
"dependsOn": [
"pkg:maven/xxxx",
"pkg:maven/xxxxxx",
]
},
{
"ref": "pkg:from pom 3",
"dependsOn": [
"pkg:maven/xxxx",
"pkg:maven/xxxxxx",
]
},
{
"ref": "pkg:from root pom",
"dependsOn": [
"pkg:maven/xxxx",
"pkg:maven/xxxxxx",
]
},
]

I tried to use cdxgen to do this by 'cdxgen -r -t maven -o bom.json' or 'cdxgen -r -t java -o bom.json'. What we found is the bom.json generated by cdxgen do have the entire dependencies from all pom files (pom1, pom2, pom3 and root pom), but the dependencies from the root-pom were scattered and not grouped together. Only dependencies from subModule (pom1, pom2, pom3) were grouped.

[
{
"ref": "pkg:from pom 1",
"dependsOn": [
"pkg:maven/xxxx",
"pkg:maven/xxxxxx",
]
},
{
"ref": "pkg:from pom 2",
"dependsOn": [
"pkg:maven/xxxx",
"pkg:maven/xxxxxx",
]
},
{
"ref": "pkg:from pom 3",
"dependsOn": [
"pkg:maven/xxxx",
"pkg:maven/xxxxxx",
]
},
// dependencies from root pom but not been grouped
{
"ref": "pkg: others",
"dependsOn": [
"pkg:maven/xxxx",
]
},
]

Looks like the dependencies from root pom can't be grouped due to its package type 'pom' .Could someone help with this? many thanks.