anchor.diff:  Configuration config = ConfigurationProvider.getConfiguration();
   --------------------------------------------
   
  -Hereby the singleton is backed up by an instance of +ConfigurationProviderSpi+.
  +Hereby the +ConfigurationProvider+ singleton is backed up by an instance of +<<ConfigurationProviderSpi>>+.
   
   
   [[PropertyConverter]]
   ==== Property Converters
   
   As illustrated in the previous section, +Configuration+ also to access non String types. Nevertheless internally
  -all properties are strictly is modelled as pure Strings only, so non String types must be derived by converting the
  +all properties are strictly modelled as pure Strings only, so non String types must be derived by converting the
   configured String values into the required target type. This is achieved with the help of +PropertyConverters+:
   
   [source,java]
  
positive.code:                                  config);
  --------------------------------------------
  
  [[Mutability]]
  ==== Mutability
  
  tbd
  
  
  [[ConfigException]]
  === ConfigException
  
  The class +ConfigException+ models the base *runtime* exception used by the configuration system.
  
  [[SPI]]
  == SPI
  
negative.code: --------------------------------------------
  
  +PropertyConverter+ instances can be implemented and registered by default using the +ServiceLoader+. Hereby
  a configuration String value is passed to all registered converters for a type in order of their annotated +@Priority+
  value. The first non-null result of a converter is then returned as the current configuration value.
  
  Also worth mentioning is the fact, that the +PropertyConverter+ to be used can also be explicitly defined, when
  a configuration value is accessed, by using the methods
  +<T> Optional<T> Configuration#getOptional(String, PropertyConverter<T> converter)+ (Java 8 only) and
  +<T> T Configuration#get(String, PropertyConverter<T> converter)+.
  
  Access to converters is provided by the current +ConfigurationContext+, which is accessible from
  the +ConfigurationProvider+ singleton.
  