Some minor code improvements

src/main/java/at/ac/uibk/gitsearch/service/EditorialPagesService.java

@@ -2,6 +2,9 @@ package at.ac.uibk.gitsearch.service;
 
 import java.io.UnsupportedEncodingException;
 import java.net.URLEncoder;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+import java.nio.charset.UnsupportedCharsetException;
 
 import org.gitlab4j.api.GitLabApiException;
 import org.gitlab4j.api.models.WikiPage;
@@ -36,11 +39,7 @@ public class EditorialPagesService {
 	@Cacheable(PAGES_CACHE)
 	public EditorialPageDTO getContent(String path) throws GitLabApiException {
 		String encodedPath;
-		try {
-			encodedPath = URLEncoder.encode(path, "UTF-8");
-		} catch (UnsupportedEncodingException e) {
-			encodedPath = URLEncoder.encode(path);
-		}
+		encodedPath = URLEncoder.encode(path, StandardCharsets.UTF_8);
 		final WikiPage page = gitLabRepository.getGitLabApi().getWikisApi().getPage(editorialProject, encodedPath);
 		return new EditorialPageDTO(path, page.getContent());
 	}

src/main/java/at/ac/uibk/gitsearch/service/ExerciseService.java

@@ -9,6 +9,7 @@ import java.io.InputStream;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URLDecoder;
+import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
@@ -180,7 +181,7 @@ public class ExerciseService {
             jsonObject.put("type", "programming exercise");
         }
 
-        try (FileWriter fileWriter = new FileWriter(jsonFile)) {
+        try (FileWriter fileWriter = new FileWriter(jsonFile, StandardCharsets.UTF_8)) {
         	fileWriter.write(jsonObject.toString(JSONStyle.NO_COMPRESS));
         }
     }

src/test/java/at/ac/uibk/gitsearch/repository/gitlab/TestMetaDataGenerator.java

@@ -4,6 +4,7 @@ import java.io.File;
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -45,7 +46,7 @@ public class TestMetaDataGenerator {
 	
 		fileContent = Files.readAllBytes(f.toPath());
 		if(f.getName().endsWith(".yaml")) {
-			String content = new String(fileContent, "UTF-8");
+			String content = new String(fileContent, StandardCharsets.UTF_8);
 			return content.replace("${title}", "Meta Test Data " + count).replace("${keyword}", "testing" + count).getBytes();
 		} else {
 			return fileContent;

src/test/java/at/ac/uibk/gitsearch/repository/search/testESService/ElasticSearchTestConfiguration.java

@@ -9,6 +9,7 @@ import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLEncoder;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.time.Duration;
 import java.time.Instant;
 import java.time.temporal.ChronoUnit;
@@ -647,7 +648,7 @@ public class ElasticSearchTestConfiguration {
 				return metaDataStream;
 			}
 		};
-		String text = byteSource.asCharSource(Charsets.UTF_8).read();
+		String text = byteSource.asCharSource(StandardCharsets.UTF_8).read();
 		return text;
 	}
 

src/test/java/at/ac/uibk/gitsearch/service/ExerciseServiceIT.java

@@ -8,6 +8,7 @@ import static org.mockito.Mockito.verify;
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.List;
@@ -106,7 +107,7 @@ public class ExerciseServiceIT {
         File metadata = new File("tmp-import/" + token, "Exercise-Details-something.json");
         metadata.getParentFile().mkdirs();
         metadata.createNewFile();
-        FileWriter writer = new FileWriter(metadata);
+        FileWriter writer = new FileWriter(metadata, StandardCharsets.UTF_8);
         writer.write("{\n" + "  \"metadataVersion\": \"1\",\n" + "  \"type\": \"programming exercise\",\n"
                 + "  \"title\": \"TestTitle\",\n" + "  \"license\": \"testLicense\",\n" + "  \"maxPoints\": 100,\n"
                 + "  \"bonusPoints\": 100,\n" + "  \"mode\": \"INDIVIDUAL\",\n" + "  \"staticCodeAnalysis\": false,\n"
@@ -138,7 +139,7 @@ public class ExerciseServiceIT {
         File metadata = new File("tmp-import/" + token, "Exercise-Details-something.json");
         metadata.getParentFile().mkdirs();
         metadata.createNewFile();
-        FileWriter writer = new FileWriter(metadata);
+        FileWriter writer = new FileWriter(metadata, StandardCharsets.UTF_8);
         writer.write("{\n" + "  \"metadataVersion\": \"1\",\n" + "  \"type\": \"programming exercise\",\n"
                 + "  \"title\": \"TestTitle\",\n" + "  \"license\": \"testLicense\"\n" + "}");
         writer.close();

src/test/java/at/ac/uibk/gitsearch/testingUtilities/PropertiesTester.java

@@ -131,7 +131,7 @@ public void testSetters(Class<?> beanClass, Object bean, String... setterExcepti
             property = null;
           }
         } else if(Set.class.isAssignableFrom(type)) {
-        	property = Collections.EMPTY_SET;
+        	property = Collections.emptySet();
         } else if (Instant.class.isAssignableFrom(type)) {
         	property = Instant.now();
         } else if (Float.class.isAssignableFrom(type)) {