docs: function( feature ) {
  			if ( this.disabled )
  				return true;
  
  			if ( !feature )
  				return true;
  
  			// Some features may want to register other features.
  			// E.g. a button may return a command bound to it.
  			if ( feature.toFeature )
  				feature = feature.toFeature( this.editor );
  
  			// If default configuration (will be checked inside #allow()),
  			// then add allowed content rules.
  			this.allow( feature.allowedContent, feature.name );
  
  			this.addTransformations( feature.contentTransformations );
  			this.addContentForms( feature.contentForms );
  
  			// If custom configuration or any DACRs, then check if required content is allowed.
  			if ( feature.requiredContent && ( this.customConfig || this.disallowedContent.length ) )
  				return this.check( feature.requiredContent );
  
  			return true;
  		}