Update guide-exceptions.asciidoc

Author: hohwille

documentation/guide-exceptions.asciidoc

@@ -84,6 +84,7 @@ For catching and handling exceptions we follow these rules:
 * If we catch an exception and throw a new one, we always *have* to provide the original exception as http://docs.oracle.com/javase/7/docs/api/java/lang/Throwable.html#getCause%28%29[cause] to the constructor of the new exception.
 * At the entry points of the application (e.g. a service operation) we have to catch and handle all throwables. This is done via the _exception-facade-pattern_ via an explicit facade or aspect. The devon4j already provides ready-to-use implementations for this such as https://github.com/devonfw/devon4j/blob/develop/modules/rest/src/main/java/com/devonfw/module/rest/service/impl/RestServiceExceptionFacade.java[RestServiceExceptionFacade]. The exception facade has to...
 ** log all errors (user errors on info and technical errors on error level)
+** ensure the entire exception is passed to the logger (not only the message) so that the logger can capture the entire stacktrace and the root cause is not lost.
 ** convert the error to a result appropriable for the client and secure for https://www.owasp.org/index.php/Top_10_2013-A6-Sensitive_Data_Exposure[Sensitive Data Exposure]. Especially for security exceptions only a generic security error code or message may be revealed but the details shall only be logged but *not* be exposed to the client. All _internal exceptions_ are converted to a generic error with a message like:
 +
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