Kotlin + Jackson Pretty Print Override

JsonTest.kt

package org.utkuozdemir.json

import com.fasterxml.jackson.core.util.DefaultPrettyPrinter
import com.fasterxml.jackson.core.util.Separators
import com.fasterxml.jackson.databind.ObjectMapper
import org.junit.jupiter.api.Test

data class Person(val name: String, val age: Int)

class CustomPrettyPrinter : DefaultPrettyPrinter() {
    override fun createInstance(): CustomPrettyPrinter {
        return CustomPrettyPrinter()
    }

    override fun withSeparators(separators: Separators?): CustomPrettyPrinter {
        super.withSeparators(separators)
        _objectFieldValueSeparatorWithSpaces = _objectFieldValueSeparatorWithSpaces.trimStart()
        return this
    }
}

class JsonTest {
    @Test
    fun testJson() {
        val objectMapper = ObjectMapper()
        val prettyPrinter = CustomPrettyPrinter()
        objectMapper.setDefaultPrettyPrinter(prettyPrinter)
        val json = objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(Person("Utku", 33))
        println(json)
    }
}

Removes the trailing space on field value separator from the Jackson pretty printer, so the fields print like "foo": "bar" instead of "foo" : "bar".

The code above outputs:

{
  "name": "Utku",
  "age": 33
}