有MapperFeature.ALLOW_COERCION_OF_SCALARS。如果设置为false，它将阻止ObjectMapper将数字和布尔值的String表示形式强制转换为Java对应形式。只允许严格转换。
下面是它的用法示例

package com.stackoverflow

import com.fasterxml.jackson.databind.MapperFeature
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.exc.MismatchedInputException
import com.fasterxml.jackson.module.kotlin.registerKotlinModule
import org.junit.jupiter.api.Assertions.assertEquals
import org.junit.jupiter.api.Assertions.assertNull
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.assertThrows

data class JSON(
    val name: String,
    val age: Int?
)

class ObjectMapperTest {

    private val objectMapper =
        ObjectMapper()
            .registerKotlinModule()
            .configure(MapperFeature.ALLOW_COERCION_OF_SCALARS, false)

    @Test
    fun mapStringTest() {
        assertThrows<MismatchedInputException> {
            objectMapper.readValue(
                """
            {
              "name": "testName",
              "age": "null"
            }
            """.trimIndent(),
                JSON::class.java
            )
        }

        assertThrows<MismatchedInputException> {
            objectMapper.readValue(
                """
            {
              "name": "testName",
              "age": "1"
            }
            """.trimIndent(),
                JSON::class.java
            )
        }

        assertEquals(1,  objectMapper.readValue(
            """
            {
              "name": "testName",
              "age": 1
            }
            """.trimIndent(),
            JSON::class.java
        ).age)

        assertNull(objectMapper.readValue(
            """
            {
              "name": "testName"
            }
            """.trimIndent(),
            JSON::class.java
        ).age)
    }
}