SONARJAVA-4645 Fix unchecked NPE on initializer on S6806 (4497)

Author: erwan-serandour

java-checks-test-sources/src/main/java/checks/spring/ModelAttributeNamingConventionForSpELCheck.java

@@ -3,6 +3,7 @@
 import java.io.File;
 import java.util.HashMap;
 import java.util.Map;
+import org.springframework.ui.Model;
 
 class ModelAttributeNamingConventionForSpELCheck {
 
@@ -42,6 +43,13 @@ public void foo(org.springframework.ui.Model model) {
     model.addAttribute("$d", 8); // Compliant
 
     model.addAllAttributes(new HashMap<>()); // Compliant - test coverage
+    model.addAllAttributes(Map.of());
+
+
+  }
+
+  public void modelAttribute(Model model, String name, Object value) { // Compliant
+    model.addAttribute(name, value);
   }
 
   private Map getMap() {

java-checks/src/main/java/org/sonar/java/checks/spring/ModelAttributeNamingConventionForSpELCheck.java

@@ -91,7 +91,7 @@ private void checkStringLiteralAndReport(ExpressionTree tree, ExpressionTree rep
 
   private void checkIdentifier(IdentifierTree identifierTree) {
     VariableTreeImpl declaration = (VariableTreeImpl) identifierTree.symbol().declaration();
-    if (declaration != null) {
+    if (declaration != null && declaration.initializer()!=null) {
       checkExpression(declaration.initializer(), identifierTree);
     }
   }