Provide a setter for validationException

If a subclass needs to extend isValid(String), it must be able to set
the validation exception. In fact, overriding any of the non-private
validateXXX methods is trivial, because a ValidationError can simply be
thrown, but if additional validation is required, which is not covered
by any of those validateXXX methods, a subclass may need to override
isValid(String) directly, and this does not throw ValidationError, but
rather catches it so that it can be subsequently returned by
getValidationException() to the consumer. Hence, a setter with at least
protected visibility is needed for subclasses to do the same.

Author: mauromol

core/src/main/java/com/onelogin/saml2/authn/SamlResponse.java

@@ -1022,6 +1022,17 @@ public String getError() {
 	public Exception getValidationException() {
 		return validationException;
 	}
+	
+	/**
+	 * Sets the validation exception that this {@link SamlResponse} should return
+	 * when a validation error occurs.
+	 * 
+	 * @param validationException
+	 *              the validation exception to set
+	 */
+	protected void setValidationException(Exception validationException) {
+		this.validationException = validationException;
+	}
 
 	/**
 	 * Extracts a node from the DOMDocument (Assertion).