[java-inspections] IDEA-374865 ClassCanBeRecord: make containingClass local in ConstructorBodyProcessor

Replaced the field with a local variable to simplify the class structure.

In response to IJ-CR-167896

GitOrigin-RevId: d1678890cdb3733d7f670a5d63c6d854e1926b0c

java/java-impl-inspections/src/com/intellij/codeInspection/classCanBeRecord/ConstructorBodyProcessor.java

@@ -19,7 +19,6 @@ import static com.intellij.psi.PsiModifier.STATIC;
 
 @NotNullByDefault
 final class ConstructorBodyProcessor {
-  private final PsiClass containingClass;
   private final PsiMethod constructor;
   private final Map<PsiParameter, @Nullable PsiField> paramsToFields = new HashMap<>();
   // TODO(bartekpacia): change type to SequencedMap once we move to Java 21
@@ -42,7 +41,6 @@ final class ConstructorBodyProcessor {
 
   ConstructorBodyProcessor(PsiMethod constructor,
                            List<PsiField> instanceFields) {
-    this.containingClass = Objects.requireNonNull(constructor.getContainingClass(), "constructor must have containing class");
     this.constructor = constructor;
     this.instanceFields = instanceFields;
     final PsiCodeBlock body = Objects.requireNonNull(constructor.getBody(), "constructor must have body");
@@ -60,6 +58,9 @@ final class ConstructorBodyProcessor {
     }
     final PsiExpression expression = expressionStatement.getExpression();
 
+    final PsiClass containingClass = constructor.getContainingClass();
+    if (containingClass == null) return;
+
     if (expression instanceof PsiMethodCallExpression methodCallExpr && JavaPsiConstructorUtil.isChainedConstructorCall(methodCallExpr)) {
       delegating = true;
       for (PsiExpression arg : methodCallExpr.getArgumentList().getExpressions()) {