Add new exception MDImporterWritingIsDisabled

exceptions/updates/MDImporterWritingIsDisabled.php

@@ -0,0 +1,19 @@
+<?PHP
+declare(strict_types = 1);
+
+/**
+ * Exception thrown when trying to use the importer's write() methods during dry run.
+ * are not set public.
+ */
+final class MDImporterWritingIsDisabled extends Exception {
+    /**
+     * Error message.
+     *
+     * @return string
+     */
+    public function errorMessage() {
+        //error message
+        return 'Inputs are not valid.';
+
+    }
+}