Custom parameters (`$count=true`) are not rendered for `$expand`

[eugene-andreev]

Issue descritpion

Given the following code snippets:

StructuredQuery s = StructuredQuery.onEntity("A", V4)
            .select(StructuredQuery.onEntity("B", V4) // isRoot = true
                    .withInlineCount());

s.getQueryString();

Output: $expand=B($count=true) 👍

StructuredQuery s2 = StructuredQuery.onEntity("A", V4)
            .select(StructuredQuery.asNestedQueryOnProperty("B", V4) // isRoot = false
                    .withInlineCount());

s2.getQueryString();

Output: $expand=B unexpected 👎

---

Root cause

The issue is that the QuerySerializer checks the query.isRoot() and renders custom parameters only if statement is true. However for the inlineCount option of an expanded subquery this fails and produces the wrong result.

As CAP Java relies on the Cloud SDK impl and translates the CDS queries generically this causes the issues for our stakeholders.
I see here 2 options:

1. either add a whitelist of custom parameters to be always rendered (disregarding whether it's root or not), like inlineCount;
2. simply render all custom params that the user specified.

Steps to Reproduce

    StructuredQuery s = StructuredQuery.onEntity("A", V4)
            .select(StructuredQuery.onEntity("B", V4) // root
                    .withInlineCount());

Output: $expand=B($count=true) as expected

    StructuredQuery s2 = StructuredQuery.onEntity("A", V4)
            .select(StructuredQuery.asNestedQueryOnProperty("B", V4) // nested
                    .withInlineCount());

Output: $expand=B unexpected

Expected Behavior

Output: $expand=B($count=true)

Used Versions

Apache Maven 3.9.12
Java version: 25.0.3, vendor: SAP SE
CAP Java: 5.0.0-SNAPSHOT

[eugene-andreev]

According to odata-abnf-construction-rules.txt the inlinecount = ( "$count" / "count" ) EQ booleanValue should not be treated as a custom parameter, rather the part of an

expandRefOption   = expandCountOption
                  / orderby
                  / skip 
                  / top 
                  / inlinecount

The same way as skip, top etc