code: @SuppressWarnings("unchecked")
      public Declaration getDeclaration(final String identifier) {
          if ( this.dirty || (this.declarations == null) ) {
              this.declarations = this.getExtendedLhs( this, null ).getOuterDeclarations();
              this.dirty = false;
          }
          return this.declarations.get( identifier );
      }
docs: Retrieve a parameter <code>Declaration</code> by identifier.
  
  @param identifier
  The identifier.
  
  @return The declaration or <code>null</code> if no declaration matches
  the <code>identifier</code>.