sometime the prefix 'gmd' is not assigned to the GMD namespace

src/main/java/de/landsh/opendata/csw2dcat/MDMetadata2Dataset.java

@@ -378,6 +378,7 @@ public class MDMetadata2Dataset {
             throw new IllegalArgumentException("Input must be a gmd:MD_Metadata element.");
         }
 
+        metadata.addNamespace("gmd", "http://www.isotc211.org/2005/gmd");
         if (null == metadata.selectSingleNode("gmd:hierarchyLevel/gmd:MD_ScopeCode[@codeListValue='service']")) {
             throw new IllegalArgumentException("Input is not a service");
         }

src/test/java/de/landsh/opendata/csw2dcat/MDMetadata2DatasetTests.java

@@ -1069,6 +1069,16 @@ public class MDMetadata2DatasetTests {
         assertTrue(result.isEmpty());
     }
 
+    /**
+     * The gmd prefix is not bound in this document.
+     */
+    @Test
+    public void convertServiceToDistributions_noGmdPrefix() throws Exception{
+        final Document inputDocument = saxReader.read(getClass().getResourceAsStream("/d65a2641-1a2e-4011-b729-2e5578efe68c.xml"));
+        Collection<Resource> result = service.convertServiceToDistributions(inputDocument.getRootElement());
+        assertNotNull(result);
+        assertEquals(1, result.size());
+    }
 
     /**
      * Parameter is not a gmd:MD_Metadata element.