Code Insight: "Generate equals/hashCode" action

idea/testData/codeInsight/generate/equalsWithHashCode/singleVarNullable.kt.after

@@ -0,0 +1,20 @@
+class A(val n: Int?) {
+    fun foo() {
+
+    }
+
+    <caret>override fun equals(other: Any?): Boolean{
+        if (this === other) return true
+        if (other?.javaClass != javaClass) return false
+
+        other as A
+
+        if (n != other.n) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int{
+        return n ?: 0
+    }
+}