Add test for #757

Author: k163377

src/test/kotlin/com/fasterxml/jackson/module/kotlin/test/github/GitHub757.kt

@@ -0,0 +1,22 @@
+package com.fasterxml.jackson.module.kotlin.test.github
+
+import com.fasterxml.jackson.databind.json.JsonMapper
+import com.fasterxml.jackson.module.kotlin.KotlinFeature
+import com.fasterxml.jackson.module.kotlin.KotlinModule
+import com.fasterxml.jackson.module.kotlin.convertValue
+import kotlin.test.Test
+import kotlin.test.assertNull
+
+class GitHub757 {
+    @Test
+    fun test() {
+        val kotlinModule = KotlinModule.Builder()
+            .enable(KotlinFeature.StrictNullChecks)
+            .build()
+        val mapper = JsonMapper.builder()
+            .addModule(kotlinModule)
+            .build()
+        val convertValue = mapper.convertValue<String?>(null)
+        assertNull(convertValue)
+    }
+}