Fixes file extension handling

Signed-off-by: Frank Schnicke <frank.schnicke@iese.fraunhofer.de>

pom.xml

@@ -356,6 +356,12 @@
 			<version>5.2.1</version>
 			<scope>test</scope>
 		</dependency>
+
+		<dependency>
+		    <groupId>org.apache.tika</groupId>
+		    <artifactId>tika-core</artifactId>
+		    <version>2.7.0</version>
+		</dependency>
 	</dependencies>
 
 	<dependencyManagement>

src/main/java/org/eclipse/basyx/submodel/restapi/vab/VABSubmodelAPI.java

@@ -33,6 +33,9 @@
 import java.util.stream.Collectors;
 
 import org.apache.commons.io.IOUtils;
+import org.apache.tika.mime.MimeType;
+import org.apache.tika.mime.MimeTypeException;
+import org.apache.tika.mime.MimeTypes;
 import org.eclipse.basyx.submodel.metamodel.api.ISubmodel;
 import org.eclipse.basyx.submodel.metamodel.api.submodelelement.ISubmodelElement;
 import org.eclipse.basyx.submodel.metamodel.api.submodelelement.operation.IOperation;
@@ -173,7 +176,20 @@ private void createFile(String idShortPath, Object newValue, ISubmodelElement su
 	private String getFilePath(String idShortPath, File file) {
 		String fileName = idShortPath.replaceAll("/", "-");
 
-		return tmpDirectory + "/" + fileName;
+		String extension = getFileExtension(file);
+
+		return tmpDirectory + "/" + fileName + extension;
+	}
+
+	private String getFileExtension(File file) {
+		MimeTypes allTypes = MimeTypes.getDefaultMimeTypes();
+		try {
+			MimeType mimeType = allTypes.forName(file.getMimeType());
+			return mimeType.getExtension();
+		} catch (MimeTypeException e) {
+			e.printStackTrace();
+			return "";
+		}
 	}
 
 	@Override

src/test/java/org/eclipse/basyx/testsuite/regression/submodel/restapi/TestFileSubmodelElement.java

@@ -67,7 +67,7 @@ public void fileIsUploadedCorrectly() throws IOException {
 
 		java.io.File file = submodelAPI.getSubmodelElementFile(FILE_SME_ID_SHORT);
 
-		assertEquals("fileSmeIdShort", file.getName());
+		assertEquals("fileSmeIdShort.xml", file.getName());
 		assertEquals(tempFile.length(), file.length());
 	}