Java API not querying as I would expect - elasticsearch

Question

I'm using the newer 8.1 Java API for Elastic in Kotlin, and getting behavior that isn't what I would expect, nor what I get when using the manual REST API. Here's my code:
val boolQuery = BoolQuery.of { boolBuilder -> boolBuilder
.must { mustBuilder ->
query.forEachIndexed { index, char ->
val prefix = if (index > 0) {
"* "
} else { "" }
val queryString = QueryStringQuery.of { queryBuilder -> queryBuilder
.query("${prefix}${char}*")
}
mustBuilder.queryString(queryString)
}
mustBuilder
}
}
In practice this only appears to hit on the last string query. With an input of query="rp" I would expect the following request to be made:
{
"query": {
"bool" : {
"must" : [
{ "query_string" : { "query" : "r*" } },
{ "query_string" : { "query" : "* p*" } }
]
}
}
}
When running that exact request, it does behave as I expect/intend. I can't tell how to pull out the request the Java API is sending over without monitoring the traffic, but if I understand the pattern then I would think these are isomorphic. I've also confirmed that the Kotlin code is calling the Java API as intended based on my input.
What am I doing wrong here?

Answer 1

Apparently asking the question was enough to figure it out – each subquery needs its own builder. Here's the modified code now working as expected:
val boolQuery = BoolQuery.of { boolBuilder ->
query.forEachIndexed { index, char ->
val prefix = if (index > 0) {
"* "
} else { "" }
boolBuilder.must { mustBuilder ->
val queryString = QueryStringQuery.of { queryBuilder -> queryBuilder
.query("${prefix}${char}*")
}
mustBuilder.queryString(queryString)
}
}
boolBuilder
}