[FIR] Fix determining nullability of arguments during enhancement

compiler/fir/analysis-tests/testData/resolve/arguments/typeMismatchOnExpectedJavaMap.fir.txt

@@ -0,0 +1,4 @@
+FILE: main.kt
+    public final fun <T> test(executor: R|BuildActionExecuter<T>|, modelType: R|java/lang/Class<T>|, env: R|kotlin/collections/Map<kotlin/String, kotlin/String>|): R|kotlin/Unit| {
+        lval model: R|ft<BuildActionExecuter<ft<T, T?>!>, BuildActionExecuter<ft<T, T?>!>?>!| = R|<local>/executor|.R|SubstitutionOverride</BuildActionExecuter.setEnvironmentVariables: R|ft<BuildActionExecuter<ft<T, T?>!>, BuildActionExecuter<ft<T, T?>!>?>!|>|(R|<local>/env|)
+    }

compiler/fir/analysis-tests/testData/resolve/arguments/typeMismatchOnExpectedJavaMap.kt

@@ -0,0 +1,26 @@
+// FULL_JDK
+
+// FILE: LongRunningOperation.java
+import java.util.Map;
+import org.jetbrains.annotations.Nullable;
+
+public interface LongRunningOperation {
+    LongRunningOperation setEnvironmentVariables(@Nullable Map<String, String> envVariables);
+}
+
+// FILE: ConfigurableLauncher.java
+import java.util.Map;
+
+public interface ConfigurableLauncher<T extends ConfigurableLauncher<T>> extends LongRunningOperation {
+    @Override
+    T setEnvironmentVariables(Map<String, String> envVariables);
+}
+
+// FILE: BuildActionExecuter.java
+public interface BuildActionExecuter<T> extends ConfigurableLauncher<BuildActionExecuter<T>> {}
+
+// FILE: main.kt
+
+fun <T> test(executor: BuildActionExecuter<T>, modelType: Class<T>, env: Map<String, String>) {
+    val model = executor.setEnvironmentVariables(env)
+}