[FIR] Implement warnings for java nullability type mismatch on override

#KT-56989

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -5025,6 +5025,14 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirJvmErrors.WRONG_NULLABILITY_FOR_JAVA_OVERRIDE) { firDiagnostic ->
+        WrongNullabilityForJavaOverrideImpl(
+            firSymbolBuilder.callableBuilder.buildCallableSymbol(firDiagnostic.a),
+            firSymbolBuilder.callableBuilder.buildCallableSymbol(firDiagnostic.b),
+            firDiagnostic as KtPsiDiagnostic,
+            token,
+        )
+    }
     add(FirJvmErrors.JAVA_TYPE_MISMATCH) { firDiagnostic ->
         JavaTypeMismatchImpl(
             firSymbolBuilder.typeBuilder.buildKtType(firDiagnostic.a),

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -3495,6 +3495,12 @@ sealed interface KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = JvmInlineWithoutValueClass::class
     }
 
+    interface WrongNullabilityForJavaOverride : KtFirDiagnostic<PsiElement> {
+        override val diagnosticClass get() = WrongNullabilityForJavaOverride::class
+        val override: KtCallableSymbol
+        val base: KtCallableSymbol
+    }
+
     interface JavaTypeMismatch : KtFirDiagnostic<KtExpression> {
         override val diagnosticClass get() = JavaTypeMismatch::class
         val expectedType: KtType

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -4217,6 +4217,13 @@ internal class JvmInlineWithoutValueClassImpl(
     token: KtLifetimeToken,
 ) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtFirDiagnostic.JvmInlineWithoutValueClass
 
+internal class WrongNullabilityForJavaOverrideImpl(
+    override val override: KtCallableSymbol,
+    override val base: KtCallableSymbol,
+    firDiagnostic: KtPsiDiagnostic,
+    token: KtLifetimeToken,
+) : KtAbstractFirDiagnostic<PsiElement>(firDiagnostic, token), KtFirDiagnostic.WrongNullabilityForJavaOverride
+
 internal class JavaTypeMismatchImpl(
     override val expectedType: KtType,
     override val actualType: KtType,