handle default package

Author: Lulu13022002

src/main/java/io/papermc/typewriter/ClassNamed.java

@@ -18,7 +18,7 @@ public ClassNamed(Class<?> knownClass) {
     }
 
     public ClassNamed {
-        Preconditions.checkArgument(SourceVersion.isName(packageName), "Package name contains syntax errors");
+        Preconditions.checkArgument(packageName.isEmpty() || SourceVersion.isName(packageName), "Package name contains syntax errors");
         Preconditions.checkArgument(SourceVersion.isName(dottedNestedName), "Class name contains syntax errors");
         if (knownClass != null) {
             Preconditions.checkArgument(!knownClass.isPrimitive(), "Invalid class, primitive types and 'void' type are not allowed");
@@ -29,7 +29,7 @@ public ClassNamed(Class<?> knownClass) {
     /**
      * Creates a class named object.
      *
-     * @param packageName the package name
+     * @param packageName the package name or an empty string for the default package
      * @param name        the class name
      * @return the new object
      * @apiNote nested classes are delimited by '$' character and
@@ -54,7 +54,7 @@ public static ClassNamed of(String packageName, String name) {
     /**
      * Creates a class named object.
      *
-     * @param packageName the package name
+     * @param packageName the package name or an empty string for the default package
      * @param name        the root class name
      * @param nestedNames the nested class names
      * @return the new object
@@ -124,6 +124,10 @@ public String canonicalName() {
             return this.knownClass.getCanonicalName();
         }
 
+        if (this.packageName.isEmpty()) {
+            return this.dottedNestedName;
+        }
+
         return this.packageName + '.' + this.dottedNestedName;
     }
 

src/main/java/io/papermc/typewriter/utils/ClassHelper.java

@@ -17,7 +17,11 @@ public static Class<?> getRootClass(Class<?> clazz) {
 
     public static String retrieveFullNestedName(Class<?> clazz) {
         String fqn = clazz.getCanonicalName();
-        return fqn.substring(clazz.getPackageName().length() + 1);
+        String packageName = clazz.getPackageName();
+        if (packageName.isEmpty()) {
+            return fqn;
+        }
+        return fqn.substring(packageName.length() + 1);
     }
 
     private ClassHelper() {