[Test] Reproduce KT-79816

Author: demiurg906

analysis/low-level-api-fir/tests-gen/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLBlackBoxTestGenerated.java

@@ -0,0 +1,42 @@
+// TARGET_BACKEND: JVM_IR
+// IGNORE_BACKEND_K2: JVM_IR
+// FULL_JDK
+// ISSUE: KT-79816
+
+// FILE: JavaSupplier.java
+public interface JavaSupplier<V> {
+    public V get();
+}
+
+// FILE: main.kt
+import java.util.function.Supplier
+
+fun interface KotlinSupplier<V> {
+    fun get(): V
+}
+
+class KotlinSupplierProxy<V>(supplier: KotlinSupplier<V>) : KotlinSupplier<V> by supplier
+class JavaManualSupplierProxy<V>(supplier: JavaSupplier<V>) : JavaSupplier<V> by supplier
+class JavaStdlibSupplierProxy<V>(supplier: Supplier<V>) : Supplier<V> by supplier
+
+fun requireNull(x: Any?) {
+    if (x != null) {
+        throw IllegalStateException("Value is not null: $x")
+    }
+}
+
+fun box(): String {
+    val nullKotlinSupplier = KotlinSupplier<Boolean?> { null }
+    val kotlinProxy = KotlinSupplierProxy(nullKotlinSupplier)
+    requireNull(kotlinProxy.get())
+
+    val nullManualJavaSupplier = JavaSupplier<Boolean?> { null }
+    val javaManualProxy = JavaManualSupplierProxy(nullManualJavaSupplier)
+    requireNull(javaManualProxy.get())
+
+    val nullJavaStdlibSupplier = Supplier<Boolean?> { null }
+    val javaStdlibProxy = JavaStdlibSupplierProxy(nullJavaStdlibSupplier)
+    requireNull(javaStdlibProxy.get())
+
+    return "OK"
+}