meet syntax-error when `abstract class` without `public`

[Anilople]

code

abstract class AbstractResource {
  private String path;

  public String getPath() {
    return path;
  }

  public void setPath(String path) {
    this.path = path;
  }
}

the puml generated

@startuml
package com.ctrip.framework.apollo.openapi.client.service {
  abstract ~class AbstractResource {
    - path : String
    ~ AbstractResource()
    + getPath() : String
    + setPath(path : String)
  }
}
@enduml

fail to compile by puml becasue ~ in ~class

when change ~class to class, it work.