Fix cases where a package private nested public class causes a compile error

inject-generator/src/main/java/io/avaje/inject/generator/SimpleModuleWriter.java

@@ -23,6 +23,7 @@
 
 import javax.lang.model.element.ElementKind;
 import javax.lang.model.element.Modifier;
+import javax.lang.model.element.NestingKind;
 import javax.lang.model.element.TypeElement;
 import javax.tools.FileObject;
 
@@ -261,14 +262,23 @@ private Set<String> distinctPublicClasses() {
 
         String type = Util.trimGenerics(rawType);
         TypeElement element = typeElement(type);
-        if (element != null && element.getModifiers().contains(Modifier.PUBLIC)) {
+        if (element != null
+            && element.getModifiers().contains(Modifier.PUBLIC)
+            && nestedPublic(element)) {
           publicClasses.add(type);
         }
       }
     }
     return publicClasses;
   }
 
+  private static boolean nestedPublic(TypeElement element) {
+    var enclosingElement = element.getEnclosingElement();
+    return element.getNestingKind() == NestingKind.TOP_LEVEL
+        || enclosingElement.getModifiers().contains(Modifier.PUBLIC)
+            && nestedPublic((TypeElement) enclosingElement);
+  }
+
   private void writeBuildMethod() {
     writer.append(CODE_COMMENT_CREATE_CONTEXT).eol();
     writer.append("  @Override").eol();

inject-generator/src/test/java/io/avaje/inject/generator/models/valid/pkg_private/SomeDao.java

@@ -0,0 +1,24 @@
+package io.avaje.inject.generator.models.valid.pkg_private;
+
+import io.avaje.inject.Bean;
+import io.avaje.inject.Factory;
+import io.avaje.inject.generator.models.valid.pkg_private.SomeDao.SomeMapper;
+
+interface SomeDao {
+
+  String findById(String id);
+
+  interface SomeMapper {
+
+    SomeDao someDao(String keyspace);
+  }
+}
+
+@Factory
+final class SomeUnrelatedExampleFactory {
+
+  @Bean
+  SomeMapper mapper() {
+    return null;
+  }
+}