diff --git a/src/main/java/fr/xephi/authme/datasource/SQLite.java b/src/main/java/fr/xephi/authme/datasource/SQLite.java
index ff72a8018..93b7f48a6 100644
--- a/src/main/java/fr/xephi/authme/datasource/SQLite.java
+++ b/src/main/java/fr/xephi/authme/datasource/SQLite.java
@@ -182,7 +182,11 @@ public class SQLite extends AbstractSqlDataSource {
         ConsoleLogger.info("SQLite Setup finished");
     }
 
-    protected void migrateIfNeeded() throws SQLException {
+    /**
+     * Migrates the database if necessary. See {@link SqLiteMigrater} for details.
+     */
+    @VisibleForTesting
+    void migrateIfNeeded() throws SQLException {
         DatabaseMetaData metaData = con.getMetaData();
         if (SqLiteMigrater.isMigrationRequired(metaData, tableName, col)) {
             new SqLiteMigrater(settings, dataFolder).performMigration(this);
diff --git a/src/main/java/fr/xephi/authme/datasource/mysqlextensions/XfBcryptExtension.java b/src/main/java/fr/xephi/authme/datasource/mysqlextensions/XfBcryptExtension.java
index 84ab4c953..8d2a1ee94 100644
--- a/src/main/java/fr/xephi/authme/datasource/mysqlextensions/XfBcryptExtension.java
+++ b/src/main/java/fr/xephi/authme/datasource/mysqlextensions/XfBcryptExtension.java
@@ -35,7 +35,14 @@ class XfBcryptExtension extends MySqlExtension {
             updateXenforoTablesOnSave(auth, authId.getAsInt(), con);
         }
     }
-    
+
+    /**
+     * Updates the xenforo tables after a player auth has been saved.
+     *
+     * @param auth the player auth which was saved
+     * @param id the account id
+     * @param con connection to the database
+     */
     private void updateXenforoTablesOnSave(PlayerAuth auth, int id, Connection con) throws SQLException {
         // Insert player password, salt in xf_user_authenticate
         String sql = "INSERT INTO " + xfPrefix + "user_authenticate (user_id, scheme_class, data) VALUES (?,?,?)";
diff --git a/src/main/java/fr/xephi/authme/listener/protocollib/ProtocolLibService.java b/src/main/java/fr/xephi/authme/listener/protocollib/ProtocolLibService.java
index 43d6fed47..c6acd03ef 100644
--- a/src/main/java/fr/xephi/authme/listener/protocollib/ProtocolLibService.java
+++ b/src/main/java/fr/xephi/authme/listener/protocollib/ProtocolLibService.java
@@ -79,6 +79,9 @@ public class ProtocolLibService implements SettingsDependent {
         this.isEnabled = true;
     }
 
+    /**
+     * Stops all features based on ProtocolLib.
+     */
     public void disable() {
         isEnabled = false;
 
diff --git a/src/main/java/fr/xephi/authme/security/crypts/MyBB.java b/src/main/java/fr/xephi/authme/security/crypts/MyBB.java
index 1abbe72ca..3ff0ee5e0 100644
--- a/src/main/java/fr/xephi/authme/security/crypts/MyBB.java
+++ b/src/main/java/fr/xephi/authme/security/crypts/MyBB.java
@@ -10,6 +10,7 @@ import static fr.xephi.authme.security.HashUtils.md5;
 
 @Recommendation(Usage.ACCEPTABLE)
 @HasSalt(value = SaltType.TEXT, length = 8)
+@SuppressWarnings({"checkstyle:AbbreviationAsWordInName"})
 public class MyBB extends SeparateSaltMethod {
 
     @Override
diff --git a/src/main/java/fr/xephi/authme/service/BackupService.java b/src/main/java/fr/xephi/authme/service/BackupService.java
index b85002eaa..6ae65a061 100644
--- a/src/main/java/fr/xephi/authme/service/BackupService.java
+++ b/src/main/java/fr/xephi/authme/service/BackupService.java
@@ -97,6 +97,11 @@ public class BackupService {
         return false;
     }
 
+    /**
+     * Performs a backup for the MySQL data source.
+     *
+     * @return true if successful, false otherwise
+     */
     private boolean performMySqlBackup() {
         FileUtils.createDirectory(backupFolder);
         File sqlBackupFile = constructBackupFile("sql");
diff --git a/src/main/java/fr/xephi/authme/service/GeoIpService.java b/src/main/java/fr/xephi/authme/service/GeoIpService.java
index 924e09351..804b82a15 100644
--- a/src/main/java/fr/xephi/authme/service/GeoIpService.java
+++ b/src/main/java/fr/xephi/authme/service/GeoIpService.java
@@ -226,8 +226,8 @@ public class GeoIpService {
         HashCode actualHash = function.hashBytes(Files.readAllBytes(file));
         HashCode expectedHash = HashCode.fromString(expectedChecksum);
         if (!Objects.equals(actualHash, expectedHash)) {
-            throw new IOException("GEO IP Checksum verification failed. " +
-                    "Expected: " + expectedChecksum + "Actual:" + actualHash);
+            throw new IOException("GEO IP Checksum verification failed. "
+                + "Expected: " + expectedChecksum + "Actual:" + actualHash);
         }
     }
 
@@ -267,10 +267,10 @@ public class GeoIpService {
      *
      * @param ip textual IP address to lookup.
      * @return two-character ISO 3166-1 alpha code for the country, "LOCALHOST" for local addresses
-     * or "--" if it cannot be fetched.
+     *         or "--" if it cannot be fetched.
      */
     public String getCountryCode(String ip) {
-        if(InternetProtocolUtils.isLocalAddress(ip)) {
+        if (InternetProtocolUtils.isLocalAddress(ip)) {
             return "LOCALHOST";
         }
         return getCountry(ip).map(Country::getIsoCode).orElse("--");
@@ -283,7 +283,7 @@ public class GeoIpService {
      * @return The name of the country, "LocalHost" for local addresses, or "N/A" if it cannot be fetched.
      */
     public String getCountryName(String ip) {
-        if(InternetProtocolUtils.isLocalAddress(ip)) {
+        if (InternetProtocolUtils.isLocalAddress(ip)) {
             return "LocalHost";
         }
         return getCountry(ip).map(Country::getName).orElse("N/A");
diff --git a/src/main/java/fr/xephi/authme/service/PluginHookService.java b/src/main/java/fr/xephi/authme/service/PluginHookService.java
index 0a204aa0e..ab344fac3 100644
--- a/src/main/java/fr/xephi/authme/service/PluginHookService.java
+++ b/src/main/java/fr/xephi/authme/service/PluginHookService.java
@@ -69,7 +69,7 @@ public class PluginHookService {
      */
     public File getCmiDataFolder() {
         Plugin plugin = pluginManager.getPlugin("CMI");
-        if(plugin == null) {
+        if (plugin == null) {
             return null;
         }
         return plugin.getDataFolder();
diff --git a/src/test/java/fr/xephi/authme/IsEqualByReflectionMatcher.java b/src/test/java/fr/xephi/authme/IsEqualByReflectionMatcher.java
index 55df85579..2acf5ee70 100644
--- a/src/test/java/fr/xephi/authme/IsEqualByReflectionMatcher.java
+++ b/src/test/java/fr/xephi/authme/IsEqualByReflectionMatcher.java
@@ -45,6 +45,13 @@ public final class IsEqualByReflectionMatcher<T> extends TypeSafeMatcher<T> {
         description.appendText("parameters " + expected);
     }
 
+    /**
+     * Checks that all fields of the given {@code item} are equal to the {@link #expected} object. Both objects must
+     * be exactly of the same type.
+     *
+     * @param item the object to check
+     * @return true if all fields are equal, false otherwise
+     */
     private boolean assertAreFieldsEqual(T item) {
         if (expected.getClass() != item.getClass()) {
             fail("Classes don't match, got " + expected.getClass().getSimpleName()
diff --git a/src/test/java/fr/xephi/authme/ReflectionTestUtils.java b/src/test/java/fr/xephi/authme/ReflectionTestUtils.java
index 963fbf71d..69a1e1d99 100644
--- a/src/test/java/fr/xephi/authme/ReflectionTestUtils.java
+++ b/src/test/java/fr/xephi/authme/ReflectionTestUtils.java
@@ -25,13 +25,14 @@ public final class ReflectionTestUtils {
      * @param instance the instance to modify (pass null for static fields)
      * @param fieldName the field name
      * @param value the value to set the field to
+     * @param <T> the instance type
      */
     public static <T> void setField(Class<? super T> clazz, T instance, String fieldName, Object value) {
         try {
             Field field = getField(clazz, fieldName);
             field.set(instance, value);
         } catch (IllegalAccessException e) {
-            throw new UnsupportedOperationException(
+            throw new IllegalStateException(
                 format("Could not set value to field '%s' for instance '%s' of class '%s'",
                     fieldName, instance, clazz.getName()), e);
         }
@@ -55,7 +56,7 @@ public final class ReflectionTestUtils {
             field.setAccessible(true);
             return field;
         } catch (NoSuchFieldException e) {
-            throw new UnsupportedOperationException(format("Could not get field '%s' from class '%s'",
+            throw new IllegalStateException(format("Could not get field '%s' from class '%s'",
                 fieldName, clazz.getName()), e);
         }
     }
@@ -66,13 +67,21 @@ public final class ReflectionTestUtils {
         return getFieldValue(field, instance);
     }
 
+    /**
+     * Returns the value of the field on the given instance. Wraps exceptions into a runtime exception.
+     *
+     * @param field the field to read
+     * @param instance the instance to get the value from, null if field is static
+     * @param <V> type of the field
+     * @return value of the field
+     */
     @SuppressWarnings("unchecked")
     public static <V> V getFieldValue(Field field, Object instance) {
         field.setAccessible(true);
         try {
             return (V) field.get(instance);
         } catch (IllegalAccessException e) {
-            throw new UnsupportedOperationException("Could not get value of field '" + field.getName() + "'", e);
+            throw new IllegalStateException("Could not get value of field '" + field.getName() + "'", e);
         }
     }
 
@@ -90,7 +99,7 @@ public final class ReflectionTestUtils {
             method.setAccessible(true);
             return method;
         } catch (NoSuchMethodException e) {
-            throw new UnsupportedOperationException("Could not retrieve method '" + methodName + "' from class '"
+            throw new IllegalStateException("Could not retrieve method '" + methodName + "' from class '"
                 + clazz.getName() + "'");
         }
     }
@@ -110,7 +119,7 @@ public final class ReflectionTestUtils {
         try {
             return (V) method.invoke(instance, parameters);
         } catch (InvocationTargetException | IllegalAccessException e) {
-            throw new UnsupportedOperationException("Could not invoke method '" + method + "'", e);
+            throw new IllegalStateException("Could not invoke method '" + method + "'", e);
         }
     }
 
@@ -138,7 +147,7 @@ public final class ReflectionTestUtils {
             constructor.setAccessible(true);
             return constructor.newInstance();
         } catch (ReflectiveOperationException e) {
-            throw new UnsupportedOperationException("Could not invoke no-args constructor of class " + clazz, e);
+            throw new IllegalStateException("Could not invoke no-args constructor of class " + clazz, e);
         }
     }
 }
diff --git a/src/test/java/fr/xephi/authme/command/TestCommandsUtil.java b/src/test/java/fr/xephi/authme/command/TestCommandsUtil.java
index 111eb088d..c7a2d1d3f 100644
--- a/src/test/java/fr/xephi/authme/command/TestCommandsUtil.java
+++ b/src/test/java/fr/xephi/authme/command/TestCommandsUtil.java
@@ -84,7 +84,8 @@ public final class TestCommandsUtil {
 
     /* Shortcut command to initialize a new test command. */
     private static CommandDescription createCommand(PermissionNode permission, CommandDescription parent,
-                                                    List<String> labels, Class<? extends ExecutableCommand> commandClass,
+                                                    List<String> labels,
+                                                    Class<? extends ExecutableCommand> commandClass,
                                                     CommandArgumentDescription... arguments) {
         CommandDescription.CommandBuilder command = CommandDescription.builder()
             .labels(labels)
diff --git a/src/test/java/tools/docs/translations/TranslationPageGenerator.java b/src/test/java/tools/docs/translations/TranslationPageGenerator.java
index dd87973d3..806819879 100644
--- a/src/test/java/tools/docs/translations/TranslationPageGenerator.java
+++ b/src/test/java/tools/docs/translations/TranslationPageGenerator.java
@@ -20,7 +20,8 @@ import static com.google.common.base.MoreObjects.firstNonNull;
 public class TranslationPageGenerator implements AutoToolTask {
 
     private static final String DOCS_PAGE = ToolsConstants.DOCS_FOLDER + "translations.md";
-    private static final String TEMPLATE_FILE = ToolsConstants.TOOLS_SOURCE_ROOT + "docs/translations/translations.tpl.md";
+    private static final String TEMPLATE_FILE =
+        ToolsConstants.TOOLS_SOURCE_ROOT + "docs/translations/translations.tpl.md";
     private static final Map<String, String> LANGUAGE_NAMES = buildLanguageNames();
 
     // Color configuration for the bars shown next to translation percentage
diff --git a/src/test/java/tools/messages/MessageFileVerifier.java b/src/test/java/tools/messages/MessageFileVerifier.java
index dd33e487a..650c9ff77 100644
--- a/src/test/java/tools/messages/MessageFileVerifier.java
+++ b/src/test/java/tools/messages/MessageFileVerifier.java
@@ -70,6 +70,10 @@ public class MessageFileVerifier {
         return !missingKeys.isEmpty() || !missingTags.isEmpty() || !unknownKeys.isEmpty();
     }
 
+    /**
+     * Performs the actual verification for the given file and collects all found issues into this
+     * instance's fields.
+     */
     private void verifyKeys() {
         FileConfiguration configuration = YamlConfiguration.loadConfiguration(messagesFile);
 
diff --git a/src/test/java/tools/utils/TagReplacer.java b/src/test/java/tools/utils/TagReplacer.java
index 32c744526..df3f5bdb5 100644
--- a/src/test/java/tools/utils/TagReplacer.java
+++ b/src/test/java/tools/utils/TagReplacer.java
@@ -18,7 +18,7 @@ import java.util.regex.Pattern;
  *                       version (in case the page is viewed on a fork)</li>
  * </ul>
  */
-public class TagReplacer {
+public final class TagReplacer {
 
     private TagReplacer() {
     }
diff --git a/src/test/java/tools/utils/TagValueHolder.java b/src/test/java/tools/utils/TagValueHolder.java
index 838628307..f6c9ec557 100644
--- a/src/test/java/tools/utils/TagValueHolder.java
+++ b/src/test/java/tools/utils/TagValueHolder.java
@@ -6,7 +6,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 
-public class TagValueHolder {
+public final class TagValueHolder {
 
     private Map<String, TagValue<?>> values;