Access Rules
    
Access rules can be added to build classpath entries to specify which types in the given
    entry can be accessed and which not. If the compiler detects a type access to a type that
    should not be accessed, it will create a problem marker.
    
      - Non-accessible rules define types that must not be referenced. The compiler typically
      creates an error marker for accesses to these types.
      
- Discouraged rules define types that should not be referenced. The compiler typically
      creates a warning marker for accesses to these types.
      
- Accessible rules define types that can be referenced.
      
Each rule consist of a pattern (same format as ANT patterns) and one of the rule types
    listed above.
    Each classpath entry can have any number of rules defined. The compiler will process the list
    in the order defined and take the first matching rule.
    
    The severity of the problem marker generated for accesses to 'Non-accessible' and 'Discouraged'
    type can be configured on the Java compiler's Error/Warnings
    preference page.
      
      Combine Access Rules
      Java builder
      Classpath variable
      Inclusion and exclusion patterns
      
      Java build path properties
      Error/Warnings preference page