Fix find existing builder class

Author: junkfactory

src/main/java/com/github/junkfactory/innerbuilder/generators/InnerBuilderGenerator.java

@@ -158,14 +158,14 @@ private PsiMethod generateTargetConstructor(final PsiClass targetClass, BuilderC
     @NotNull
     private BuilderClass findOrCreateBuilderClass(final PsiClass targetClass) {
         var builderClassName = Utils.buildClassName(BUILDER_CLASS_NAME, targetClass);
-        var builderClass = targetClass.findInnerClassByName(builderClassName.className(), false);
-        if (builderClass == null) {
-            builderClass = (PsiClass) targetClass.add(createBuilderClass(targetClass, builderClassName.className()));
+        var psiClass = targetClass.findInnerClassByName(BUILDER_CLASS_NAME, false);
+        if (psiClass == null) {
+            psiClass = (PsiClass) targetClass.add(createBuilderClass(targetClass, builderClassName.className()));
         }
 
         var psiElementFactory = generatorParams.psi().factory();
         var builderType = psiElementFactory.createTypeFromText(builderClassName.className(), targetClass);
-        return new BuilderClass(builderClass, builderType, builderClassName, Utils.isGenericType(builderType));
+        return new BuilderClass(psiClass, builderType, builderClassName, Utils.isGenericType(builderType));
     }
 
     @NotNull