Fix uri generation for "/" context

src/main/java/com/merkle/oss/magnolia/imaging/flexible/generator/FlexibleImageUriFactory.java

@@ -9,6 +9,7 @@
 import java.net.URI;
 import java.util.Map;
 import java.util.function.Function;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -26,7 +27,7 @@ public URI create(final FlexibleParameter parameter) {
 										".imaging",
 										FlexibleImageGenerator.GENERATOR_NAME,
 										parameter.getItemKey().asString()
-								),
+								).filter(Predicate.not(String::isBlank)),
 								parameter.toMap().entrySet().stream().sorted(Map.Entry.comparingByKey()).flatMap(p -> Stream.of(p.getKey(), p.getValue())),
 								Stream.of(parameter.getFileName())
 						).flatMap(Function.identity()).collect(Collectors.toList())

src/test/java/com/merkle/oss/magnolia/imaging/flexible/generator/FlexibleImageUriFactoryTest.java

@@ -34,4 +34,21 @@ void create() throws URISyntaxException {
 			);
 		}
 	}
+
+	@Test
+	void createNoContext() throws URISyntaxException {
+		final Asset asset = mock(Asset.class);
+		doReturn(ItemKey.from("jcr:b3ee7444-4830-4454-abbb-20fc35387032")).when(asset).getItemKey();
+		doReturn("someImage.jpg").when(asset).getFileName();
+		final FlexibleParameter parameter = new FlexibleParameter(new DynamicImageParameter(true), "16:9", 100,  asset);
+
+		try (MockedStatic<MgnlContext> mgnlContext = Mockito.mockStatic(MgnlContext.class)) {
+			mgnlContext.when(MgnlContext::getContextPath).thenReturn("/");
+
+			assertEquals(
+					new URI("/.imaging/flex/jcr:b3ee7444-4830-4454-abbb-20fc35387032/crop/true/ratio/16:9/width/100/someImage.jpg"),
+					new FlexibleImageUriFactory().create(parameter)
+			);
+		}
+	}
 }