diff --git a/.gitmodules b/.gitmodules
deleted file mode 100644
index 47f921b..0000000
--- a/.gitmodules
+++ /dev/null
@@ -1,3 +0,0 @@
-[submodule "common-utils"]
-	path = common-utils
-	url = https://git.ignuranza.net/tdlight-team/common-utils.git
diff --git a/common-utils b/common-utils
deleted file mode 160000
index 8da6756..0000000
--- a/common-utils
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 8da67564c5a006dd31c2d0528768af8f790c1a67
diff --git a/pom.xml b/pom.xml
index 8cc29db..07f4680 100644
--- a/pom.xml
+++ b/pom.xml
@@ -7,9 +7,6 @@
     <packaging>jar</packaging>
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <!-- required for jdk9 -->
-        <maven.compiler.source>10</maven.compiler.source>
-        <maven.compiler.target>10</maven.compiler.target>
     </properties>
 
     <repositories>
@@ -34,29 +31,6 @@
     </distributionManagement>
 
     <dependencies>
-        <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
-            <version>4.12</version>
-            <scope>test</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jetbrains</groupId>
-            <artifactId>annotations</artifactId>
-            <version>17.0.0</version>
-            <scope>compile</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.jetbrains</groupId>
-            <artifactId>annotations</artifactId>
-            <version>17.0.0</version>
-            <scope>compile</scope>
-        </dependency>
-        <dependency>
-            <groupId>org.warp</groupId>
-            <artifactId>common-utils</artifactId>
-            <version>1.0.3</version>
-        </dependency>
         <dependency>
             <groupId>it.tdlight</groupId>
             <artifactId>tdlight-natives-linux-amd64</artifactId>
@@ -74,36 +48,36 @@
         </dependency> 
     </dependencies>
     <build>
-        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
-            <plugins>
-                <plugin>
-                    <artifactId>maven-clean-plugin</artifactId>
-                    <version>3.0.0</version>
-                </plugin>
-                <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
-                <plugin>
-                    <artifactId>maven-resources-plugin</artifactId>
-                    <version>3.0.2</version>
-                </plugin>
-                <plugin>
-                    <artifactId>maven-compiler-plugin</artifactId>
-                    <version>3.7.0</version>
-                </plugin>
-                <plugin>
-                    <artifactId>maven-jar-plugin</artifactId>
-                    <version>3.0.2</version>
-                </plugin>
-                <plugin>
-                    <artifactId>maven-install-plugin</artifactId>
-                    <version>2.5.2</version>
-                </plugin>
-                <plugin>
-                    <artifactId>maven-deploy-plugin</artifactId>
-                    <version>2.8.2</version>
-                </plugin>
-            </plugins>
-        </pluginManagement>
         <plugins>
+            <plugin>
+                <artifactId>maven-clean-plugin</artifactId>
+                <version>3.1.0</version>
+            </plugin>
+            <plugin>
+                <artifactId>maven-resources-plugin</artifactId>
+                <version>3.0.2</version>
+            </plugin>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <version>3.8.1</version>
+                <configuration>
+                    <encoding>UTF-8</encoding>
+                    <source>8</source>
+                    <target>8</target>
+                </configuration>
+            </plugin>
+            <plugin>
+                <artifactId>maven-jar-plugin</artifactId>
+                <version>3.0.2</version>
+            </plugin>
+            <plugin>
+                <artifactId>maven-install-plugin</artifactId>
+                <version>3.0.0-M1</version>
+            </plugin>
+            <plugin>
+                <artifactId>maven-deploy-plugin</artifactId>
+                <version>2.8.2</version>
+            </plugin>
             <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>templating-maven-plugin</artifactId>
diff --git a/src/main/java/it/tdlight/tdlight/Client.java b/src/main/java/it/tdlight/tdlight/Client.java
index 6b35598..0a18185 100644
--- a/src/main/java/it/tdlight/tdlight/Client.java
+++ b/src/main/java/it/tdlight/tdlight/Client.java
@@ -59,7 +59,7 @@ public class Client extends NativeClient implements TelegramClient {
 			throw new IllegalStateException("ClientActor is destroyed");
 		}
 
-		var responseList = new ArrayList<Response>();
+		ArrayList<Response> responseList = new ArrayList<>();
 		if (eventIds == null) {
 			eventIds = new long[eventSize];
 			events = new Object[eventSize];
@@ -100,7 +100,7 @@ public class Client extends NativeClient implements TelegramClient {
 			throw new IllegalStateException("ClientActor is destroyed");
 		}
 
-		var responseList = receive(timeout, 1);
+		List<Response> responseList = receive(timeout, 1);
 
 		if (responseList.size() < 1) {
 			return null;
diff --git a/src/main/java/it/tdlight/tdlight/Init.java b/src/main/java/it/tdlight/tdlight/Init.java
index b882619..6be5ca0 100644
--- a/src/main/java/it/tdlight/tdlight/Init.java
+++ b/src/main/java/it/tdlight/tdlight/Init.java
@@ -35,7 +35,7 @@ public class Init {
      */
     public synchronized static void start() throws Throwable {
         if (!started) {
-            var os = LoadLibrary.getOs();
+            Os os = LoadLibrary.getOs();
 
             if (os == Os.win) {
                 LoadLibrary.load("libeay32");
diff --git a/src/main/java/it/tdlight/tdlight/Log.java b/src/main/java/it/tdlight/tdlight/Log.java
index d50a903..ce70437 100644
--- a/src/main/java/it/tdlight/tdlight/Log.java
+++ b/src/main/java/it/tdlight/tdlight/Log.java
@@ -1,7 +1,7 @@
 package it.tdlight.tdlight;
 
 import it.tdlight.tdlib.NativeLog;
-import java.util.Objects;
+import it.tdlight.tdlight.utils.ObjectsUtils;
 
 public class Log extends NativeLog {
 
@@ -22,7 +22,7 @@ public class Log extends NativeLog {
 	 * @param fatalErrorCallback Callback that will be called when a fatal error happens. Pass null to restore default callback.
 	 */
 	public static void setFatalErrorCallback(FatalErrorCallbackPtr fatalErrorCallback) {
-		Log.fatalErrorCallback = Objects.requireNonNullElse(fatalErrorCallback, defaultFatalErrorCallbackPtr);
+		Log.fatalErrorCallback = ObjectsUtils.requireNonNullElse(fatalErrorCallback, defaultFatalErrorCallbackPtr);
 	}
 
 	private static void onFatalError(String errorMessage) {
diff --git a/src/main/java/it/tdlight/tdlight/utils/LoadLibrary.java b/src/main/java/it/tdlight/tdlight/utils/LoadLibrary.java
index a17cff6..89373f6 100644
--- a/src/main/java/it/tdlight/tdlight/utils/LoadLibrary.java
+++ b/src/main/java/it/tdlight/tdlight/utils/LoadLibrary.java
@@ -18,6 +18,7 @@
 package it.tdlight.tdlight.utils;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.nio.ByteOrder;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -68,8 +69,8 @@ public class LoadLibrary {
 			return;
 		}
 
-		var arch = getCpuArch();
-		var os = getOs();
+		Arch arch = getCpuArch();
+		Os os = getOs();
 
 		if (arch == Arch.unknown) {
 			throw new CantLoadLibrary().initCause(new IllegalStateException("Arch: \"" + System.getProperty("os.arch") + "\" is unknown"));
@@ -99,7 +100,7 @@ public class LoadLibrary {
 	private static void loadJarLibrary(String libname, Arch arch, Os os) throws IOException, CantLoadLibrary {
 		Path tempPath = Files.createDirectories(librariesPath.resolve("version-" + libsVersion).resolve(libname));
 		Path tempFile = Paths.get(tempPath.toString(), libname + getExt(os));
-		var libInputStream = LoadLibrary.class.getResourceAsStream(createPath("libs", os.name(), arch.name(), libname) + getExt(os));
+		InputStream libInputStream = LoadLibrary.class.getResourceAsStream(createPath("libs", os.name(), arch.name(), libname) + getExt(os));
 		if (Files.notExists(tempFile)) {
 			Files.copy(libInputStream, tempFile);
 		}
@@ -109,7 +110,7 @@ public class LoadLibrary {
 
 
 	private static Arch getCpuArch() {
-		var architecture = System.getProperty("os.arch").trim();
+		String architecture = System.getProperty("os.arch").trim();
 		switch (architecture) {
 			case "amd64":
 			case "x86_64":
@@ -133,7 +134,7 @@ public class LoadLibrary {
 	}
 
 	public static Os getOs() {
-		var os = System.getProperty("os.name").toLowerCase().trim();
+		String os = System.getProperty("os.name").toLowerCase().trim();
 		if (os.contains("linux"))
 			return Os.linux;
 		if (os.contains("windows"))
@@ -150,7 +151,7 @@ public class LoadLibrary {
 	}
 
 	private static String createPath(String... path) {
-		var stringBuilder = new StringBuilder();
+		StringBuilder stringBuilder = new StringBuilder();
 		stringBuilder.append("/");
 
 		for (int i = 0; i < path.length; i++) {
diff --git a/src/main/java/it/tdlight/tdlight/utils/ObjectsUtils.java b/src/main/java/it/tdlight/tdlight/utils/ObjectsUtils.java
new file mode 100644
index 0000000..8696a76
--- /dev/null
+++ b/src/main/java/it/tdlight/tdlight/utils/ObjectsUtils.java
@@ -0,0 +1,67 @@
+package it.tdlight.tdlight.utils;
+
+public class ObjectsUtils {
+	/**
+	 * Returns the first argument if it is non-{@code null} and
+	 * otherwise returns the non-{@code null} second argument.
+	 *
+	 * @param obj an object
+	 * @param defaultObj a non-{@code null} object to return if the first argument
+	 *                   is {@code null}
+	 * @param <T> the type of the reference
+	 * @return the first argument if it is non-{@code null} and
+	 *        otherwise the second argument if it is non-{@code null}
+	 * @throws NullPointerException if both {@code obj} is null and
+	 *        {@code defaultObj} is {@code null}
+	 * @since 9
+	 */
+	public static <T> T requireNonNullElse(T obj, T defaultObj) {
+		return (obj != null) ? obj : requireNonNull(defaultObj, "defaultObj");
+	}
+
+	/**
+	 * Checks that the specified object reference is not {@code null}. This
+	 * method is designed primarily for doing parameter validation in methods
+	 * and constructors, as demonstrated below:
+	 * <blockquote><pre>
+	 * public Foo(Bar bar) {
+	 *     this.bar = Objects.requireNonNull(bar);
+	 * }
+	 * </pre></blockquote>
+	 *
+	 * @param obj the object reference to check for nullity
+	 * @param <T> the type of the reference
+	 * @return {@code obj} if not {@code null}
+	 * @throws NullPointerException if {@code obj} is {@code null}
+	 */
+	public static <T> T requireNonNull(T obj) {
+		if (obj == null)
+			throw new NullPointerException();
+		return obj;
+	}
+
+	/**
+	 * Checks that the specified object reference is not {@code null} and
+	 * throws a customized {@link NullPointerException} if it is. This method
+	 * is designed primarily for doing parameter validation in methods and
+	 * constructors with multiple parameters, as demonstrated below:
+	 * <blockquote><pre>
+	 * public Foo(Bar bar, Baz baz) {
+	 *     this.bar = Objects.requireNonNull(bar, "bar must not be null");
+	 *     this.baz = Objects.requireNonNull(baz, "baz must not be null");
+	 * }
+	 * </pre></blockquote>
+	 *
+	 * @param obj     the object reference to check for nullity
+	 * @param message detail message to be used in the event that a {@code
+	 *                NullPointerException} is thrown
+	 * @param <T> the type of the reference
+	 * @return {@code obj} if not {@code null}
+	 * @throws NullPointerException if {@code obj} is {@code null}
+	 */
+	public static <T> T requireNonNull(T obj, String message) {
+		if (obj == null)
+			throw new NullPointerException(message);
+		return obj;
+	}
+}
diff --git a/src/main/java/it/tdlight/tdlight/utils/ScannerUtils.java b/src/main/java/it/tdlight/tdlight/utils/ScannerUtils.java
index b690fe1..31609be 100644
--- a/src/main/java/it/tdlight/tdlight/utils/ScannerUtils.java
+++ b/src/main/java/it/tdlight/tdlight/utils/ScannerUtils.java
@@ -148,12 +148,12 @@ public class ScannerUtils {
 		try {
 			lock.lock();
 			StringBuilder toPrint = new StringBuilder();
-			var oldOut = System.out;
-			var oldErr = System.err;
+			PrintStream oldOut = System.out;
+			PrintStream oldErr = System.err;
 			System.setOut(emptyOut);
 			System.setErr(emptyOut);
 			oldOut.print("[" + displayName + "] " + question + ": ");
-			var result = scanner.nextLine();
+			String result = scanner.nextLine();
 			System.setOut(oldOut);
 			System.setErr(oldErr);
 			return result;