[FIR] JavaTypeParameterStack: allow nullable return from get

It is not always possible to have the correct mapping,
at least on the Analysis API side

^KT-66530 Fixed

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/methodTypeParameterWithKotlinUseSite.kt

@@ -0,0 +1,9 @@
+// FILE: KotlinClass.kt
+class Kotlin<caret_useSite>Class
+
+// FILE: A.java
+class JavaClass {
+    <TYPE> TYPE ma<caret>terialize() {
+        return null;
+    }
+}

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/methodTypeParameterWithKotlinUseSite.txt

@@ -0,0 +1,2 @@
+PsiType: PsiType:TYPE
+KtType: TYPE

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/methodTypeParameterWithMethodUseSite.kt

@@ -0,0 +1,9 @@
+// FILE: KotlinClass.kt
+class KotlinClass
+
+// FILE: A.java
+class JavaClass {
+    <TYPE> TYPE ma<caret>teria<caret_useSite>lize() {
+        return null;
+    }
+}

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/methodTypeParameterWithMethodUseSite.txt

@@ -0,0 +1,2 @@
+PsiType: PsiType:TYPE
+KtType: TYPE?

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/methodTypeParameterWithTypeParameterUseSite.kt

@@ -0,0 +1,9 @@
+// FILE: KotlinClass.kt
+class KotlinClass
+
+// FILE: A.java
+class JavaClass {
+    <TY<caret_useSite>PE> TYPE ma<caret>terialize() {
+        return null;
+    }
+}

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/methodTypeParameterWithTypeParameterUseSite.txt

@@ -0,0 +1,2 @@
+PsiType: PsiType:TYPE
+KtType: TYPE

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/typeParameterWithKotlinUseSite.kt

@@ -0,0 +1,7 @@
+// FILE: KotlinClass.kt
+class Kotlin<caret_useSite>Class
+
+// FILE: A.java
+public interface A<T> {
+    T f<caret>oo();
+}

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/typeParameterWithKotlinUseSite.txt

@@ -0,0 +1,2 @@
+PsiType: PsiType:T
+KtType: T

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/typeParameterWithMethodUseSite.kt

@@ -0,0 +1,7 @@
+// FILE: KotlinClass.kt
+class KotlinClass
+
+// FILE: A.java
+public interface A<T> {
+    T f<caret>o<caret_useSite>o();
+}

analysis/analysis-api/testData/components/psiTypeProvider/psiType/asKtType/typeParameterWithMethodUseSite.txt

@@ -0,0 +1,2 @@
+PsiType: PsiType:T
+KtType: T?