Added tests for integration of isRequired granted to various accessors

src/test/kotlin/tools/jackson/module/kotlin/test/github/GitHub668.kt

@@ -0,0 +1,46 @@
+package tools.jackson.module.kotlin.test.github
+
+import com.fasterxml.jackson.annotation.JsonProperty
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+import tools.jackson.databind.BeanDescription
+import tools.jackson.databind.ObjectMapper
+import tools.jackson.module.kotlin.defaultMapper
+import tools.jackson.module.kotlin.jacksonObjectMapper
+
+class GitHub668 {
+    private inline fun <reified T : Any> ObjectMapper.introspectDeserialization(): BeanDescription =
+        _deserializationContext().introspectBeanDescription(_deserializationContext().constructType(T::class.java))
+
+    private fun BeanDescription.isRequired(propertyName: String): Boolean =
+        this.findProperties().find { it.name == propertyName }?.isRequired ?: false
+
+    data class AffectByAccessor(
+        @get:JsonProperty(required = true)
+        var a: String?,
+        @field:JsonProperty(required = true)
+        var b: String?,
+        @set:JsonProperty(required = true)
+        var c: String?
+    ) {
+        @get:JsonProperty(required = true)
+        var x: String? = null
+        @field:JsonProperty(required = true)
+        var y: String? = null
+        @JvmField
+        @field:JsonProperty(required = true)
+        var z: String? = null
+    }
+
+    @Test
+    fun affectByAccessorTestDeser() {
+        val desc = defaultMapper.introspectDeserialization<AffectByAccessor>()
+
+        assertTrue(desc.isRequired("a"))
+        assertTrue(desc.isRequired("b"))
+        assertTrue(desc.isRequired("c"))
+        assertTrue(desc.isRequired("x"))
+        assertTrue(desc.isRequired("y"))
+        assertTrue(desc.isRequired("z"))
+    }
+}