serializing result of the isXXX fields are incompatible since 2.10.1

[tokuhirom]

Describe the bug

Serialization result of the following code is incompatible between jackson-module-kotlin 2.10.0 and 2.10.1.

data class FooKt(var isUsingBar: Boolean)

Jackson version: 2.10.0
{"usingBar":true}
Jackson version: 2.10.1
{"isUsingBar":true}

To Reproduce

here's a reproducable repository:

https://github.com/tokuhirom/jackson-field-name-incompatiblity

Expected behavior

Both 2.10.0 and 2.10.1 shows same result.

Versions
Kotlin: 1.4.10
Jackson-module-kotlin:2.10.0, 2.10.1
Jackson-databind: 2.10.0, 2.10.1

[mattluce]

It may be related to this change.
#80

[dinomite]

I like the concise explanation, but closing in favor of #346