Incorrect handling of properties starting with a single lowercase letter

[naftalmm]

Search before asking

• I searched in the issues and found nothing similar.
• I have confirmed that the same problem is not reproduced if I exclude the KotlinModule.
• I searched in the issues of databind and other modules used and found nothing similar.
• I have confirmed that the problem does not reproduce in Java and only occurs when using Kotlin and KotlinModule.

Describe the bug

Data classes with properties starting with a single lowercase letter are handled incorrectly, changing to lowercase whole group of sequential uppercase letters following it in property name:

aBcd -> abcd
aBBBBBBBBcd -> abbbbbbbbcd
aBaB -> abaB

This results in inaccurate JSON & inability to deserialize it back with the same data class.

To Reproduce

import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
import com.fasterxml.jackson.module.kotlin.readValue

data class BugTest(/*@get:JvmName("getaBcd") or @get:JsonProperty("aBcd") fixes the issue*/val aBcd: Int)

fun main() {
    val mapper = jacksonObjectMapper()
    val json = mapper.writeValueAsString(BugTest(1))
    println(json) // expected: {"aBcd":1}, actual: {"abcd":1}
    mapper.readValue<BugTest>(json) // com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "abcd" (class BugTest), not marked as ignorable (one known property: "aBcd"])
}

Expected behavior

Prints {"aBcd":1}, exits successfully.

Versions

Kotlin: Any
Jackson-module-kotlin: 2.18.2
Jackson-databind: 2.18.2

Additional context

There is a similar bug for databind, but I believe Kotlin module could handle it in its own way, since the root cause of databind's bug is a method it restores field name from getter name, while Kotlin module can directly access data class properties names and not rely on Kotlin's compiler-generated getters (which is getABcd in this case by the way).

[k163377]

Please use KotlinFeature.KotrinPropertyNameAsImplicitName.
This issue is closed as a duplicate of #630.