The class AppDatabaseConfig is an indirect subclass of DatabaseConfig so super should be present!

Compiles fine with maven compiler.

Error:(16, 17) java: cannot access company.com.MoJV.config.database.DatabaseConfig
  class file for company.com.MoJV.config.database.DatabaseConfig not found
Error:(48, 9) java: method does not override or implement a method from a supertype
Error:(50, 17) java: cannot find symbol
  symbol:   variable super
  location: class company.com.App.config.AppDatabaseConfig
Error:(53, 17) java: cannot find symbol
  symbol:   variable properties
  location: class company.com.App.config.AppDatabaseConfig
Error:(56, 25) java: cannot find symbol
  symbol:   variable properties
  location: class company.com.App.config.AppDatabaseConfig
Error:(60, 25) java: cannot find symbol
  symbol:   variable properties
  location: class company.com.App.config.AppDatabaseConfig
Error:(63, 25) java: cannot find symbol
  symbol:   variable properties
  location: class company.com.App.config.AppDatabaseConfig
Error:(66, 25) java: cannot find symbol
  symbol:   variable properties
  location: class company.com.App.config.AppDatabaseConfig
Error:(70, 25) java: cannot find symbol
  symbol:   variable properties
  location: class company.com.App.config.AppDatabaseConfig
Error:(71, 25) java: cannot find symbol
  symbol:   variable properties
  location: class company.com.App.config.AppDatabaseConfig
Error:(72, 25) java: cannot find symbol
  symbol:   variable properties
  location: class company.com.App.config.AppDatabaseConfig

  @Override
  protected void properties() {
          super.properties ( );
          ...

          properties.put(.., ..)
  }