diff --git a/java-commons/pom.xml b/java-commons/pom.xml
index 38f8a5ed..aa7f86de 100644
--- a/java-commons/pom.xml
+++ b/java-commons/pom.xml
@@ -2,11 +2,10 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
     <parent>
-        <artifactId>padla</artifactId>
         <groupId>ru.progrm-jarvis</groupId>
-        <version>1.0.0-rc.5</version>
+        <artifactId>padla</artifactId>
+        <version>1.0.0-rc.6</version>
     </parent>
     <artifactId>java-commons</artifactId>
 
@@ -49,10 +48,12 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-params</artifactId>
+            <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.hamcrest</groupId>
diff --git a/java-commons/src/main/java/ru/progrm_jarvis/javacommons/cache/CaffeineCache.java b/java-commons/src/main/java/ru/progrm_jarvis/javacommons/cache/CaffeineCache.java
index 049028b8..61abeb66 100644
--- a/java-commons/src/main/java/ru/progrm_jarvis/javacommons/cache/CaffeineCache.java
+++ b/java-commons/src/main/java/ru/progrm_jarvis/javacommons/cache/CaffeineCache.java
@@ -39,7 +39,7 @@ public class CaffeineCache {
      * @throws IllegalStateException if Caffeine is not available
      */
     public static @NotNull CacheFactory createFactory() {
-        if (AVAILABLE) return new CaffeineCacheFactory();
+        if (AVAILABLE) return CaffeineCacheFactory.INSTANCE;
 
         throw new IllegalStateException("Caffeine Cache is not available");
     }
diff --git a/java-commons/src/main/java/ru/progrm_jarvis/javacommons/data/DataSerializer.java b/java-commons/src/main/java/ru/progrm_jarvis/javacommons/data/DataSerializer.java
index ad637172..08448b83 100644
--- a/java-commons/src/main/java/ru/progrm_jarvis/javacommons/data/DataSerializer.java
+++ b/java-commons/src/main/java/ru/progrm_jarvis/javacommons/data/DataSerializer.java
@@ -10,6 +10,7 @@
 import org.jetbrains.annotations.Range;
 
 import java.io.*;
+import java.util.Optional;
 
 /**
  * Serializer of arbitary data.
@@ -194,11 +195,24 @@ default T fromByteArrayUnchecked(final byte @NotNull [] byteArray) {
      * Crates a data serializer based on this one which allows null values.
      *
      * @return null-friendly equivalent of this data serializer
+     *
+     * @see #optional() equivalent using {@link Optional} instead
      */
-    default @NotNull DataSerializer<T> nullable() {
+    default @NotNull DataSerializer<@Nullable T> nullable() {
         return new NullableDataSerializer<>(this);
     }
 
+    /**
+     * Crates a data serializer based on this one which allows {@link Optional optional} values.
+     *
+     * @return {@link Optional}-friendly equivalent of this data serializer
+     *
+     * @see #nullable() equivalent using nullable values instead
+     */
+    default @NotNull DataSerializer<@NotNull Optional<T>> optional() {
+        return new OptionalDataSerializer<>(this);
+    }
+
     /**
      * Data serializer for nullable types.
      */
@@ -220,4 +234,27 @@ public void write(final @NotNull DataOutputStream output, final @Nullable T obje
             return input.readBoolean() ? wrapped.read(input) : null;
         }
     }
+
+    /**
+     * Data serializer for {@link Optional optional} types.
+     */
+    @RequiredArgsConstructor(access = AccessLevel.PRIVATE)
+    @FieldDefaults(level = AccessLevel.PRIVATE, makeFinal = true)
+    final class OptionalDataSerializer<T> implements DataSerializer<@NotNull Optional<T>> {
+
+        @NotNull DataSerializer<T> wrapped;
+
+        @Override
+        public void write(final @NotNull DataOutputStream output,
+                          final @NotNull Optional<T> object) throws IOException {
+            final boolean present;
+            output.writeBoolean(present = object.isPresent());
+            if (present) wrapped.write(output, object.get());
+        }
+
+        @Override
+        public @NotNull Optional<T> read(final @NotNull DataInputStream input) throws IOException {
+            return input.readBoolean() ? Optional.of(wrapped.read(input)) : Optional.empty();
+        }
+    }
 }
diff --git a/padla-bom/pom.xml b/padla-bom/pom.xml
new file mode 100644
index 00000000..6379ffe0
--- /dev/null
+++ b/padla-bom/pom.xml
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>ru.progrm-jarvis</groupId>
+        <artifactId>padla</artifactId>
+        <version>1.0.0-rc.6</version>
+    </parent>
+    <artifactId>padla-bom</artifactId>
+    <packaging>pom</packaging>
+
+    <name>PADLA BOM</name>
+    <description>PADLA's Bill Of Materials</description>
+
+    <dependencyManagement>
+        <!-- Note: variables cannot be used here as this would allow version overriding -->
+        <dependencies>
+            <dependency>
+                <groupId>ru.progrm-jarvis</groupId>
+                <artifactId>java-commons</artifactId>
+                <version>1.0.0-rc.6</version>
+            </dependency>
+            <dependency>
+                <groupId>ru.progrm-jarvis</groupId>
+                <artifactId>reflector</artifactId>
+                <version>1.0.0-rc.6</version>
+            </dependency>
+            <dependency>
+                <groupId>ru.progrm-jarvis</groupId>
+                <artifactId>ultimate-messenger</artifactId>
+                <version>1.0.0-rc.6</version>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+</project>
diff --git a/pom.xml b/pom.xml
index e1c3d9d4..35382133 100644
--- a/pom.xml
+++ b/pom.xml
@@ -2,15 +2,15 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
     <groupId>ru.progrm-jarvis</groupId>
     <artifactId>padla</artifactId>
-    <version>1.0.0-rc.5</version>
+    <version>1.0.0-rc.6</version>
     <modules>
         <module>java-commons</module>
         <module>reflector</module>
         <module>ultimate-messenger</module>
         <module>tools</module>
+        <module>padla-bom</module>
     </modules>
     <packaging>pom</packaging>
 
@@ -18,9 +18,7 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <maven.compiler.source>1.8</maven.compiler.source>
         <maven.compiler.target>1.8</maven.compiler.target>
-        <!-- Testing -->
-        <version.junit>5.7.2</version.junit>
-        <version.junit.platform>1.7.2</version.junit.platform>
+        <!-- Duplicated dependency versions -->
         <version.mockito>3.12.4</version.mockito>
     </properties>
 
@@ -103,6 +101,10 @@
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-surefire-plugin</artifactId>
                     <version>3.0.0-M5</version>
+                    <configuration>
+                        <parallel>all</parallel>
+                        <useUnlimitedThreads>true</useUnlimitedThreads>
+                    </configuration>
                 </plugin>
 
                 <!-- Maven-central deployment-related plugins -->
@@ -151,6 +153,7 @@
 
     <dependencyManagement>
         <dependencies>
+            <!-- Own dependencies -->
             <dependency>
                 <groupId>${project.groupId}</groupId>
                 <artifactId>java-commons</artifactId>
@@ -162,12 +165,21 @@
                 <version>${project.version}</version>
             </dependency>
 
+            <!-- BOMs -->
+            <dependency>
+                <groupId>org.junit</groupId>
+                <artifactId>junit-bom</artifactId>
+                <version>5.8.0-RC1</version>
+                <type>pom</type>
+                <scope>import</scope>
+            </dependency>
+
             <!-- Libraries -->
             <!-- Caching -->
             <dependency>
                 <groupId>com.github.ben-manes.caffeine</groupId>
                 <artifactId>caffeine</artifactId>
-                <version>2.9.1</version>
+                <version>2.9.2</version>
                 <scope>provided</scope>
                 <optional>true</optional>
             </dependency>
@@ -175,7 +187,7 @@
             <dependency>
                 <groupId>org.ow2.asm</groupId>
                 <artifactId>asm</artifactId>
-                <version>9.1</version>
+                <version>9.2</version>
                 <scope>provided</scope>
                 <optional>true</optional>
             </dependency>
@@ -200,55 +212,18 @@
             <dependency>
                 <groupId>org.jetbrains</groupId>
                 <artifactId>annotations</artifactId>
-                <version>21.0.1</version>
+                <version>22.0.0</version>
                 <scope>provided</scope>
                 <optional>true</optional>
             </dependency>
 
             <!-- Testing -->
-            <dependency>
-                <groupId>org.junit.jupiter</groupId>
-                <artifactId>junit-jupiter-api</artifactId>
-                <version>${version.junit}</version>
-                <scope>test</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.junit.jupiter</groupId>
-                <artifactId>junit-jupiter-engine</artifactId>
-                <version>${version.junit}</version>
-                <scope>test</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.junit.jupiter</groupId>
-                <artifactId>junit-jupiter-params</artifactId>
-                <version>${version.junit}</version>
-                <scope>test</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.junit.platform</groupId>
-                <artifactId>junit-platform-launcher</artifactId>
-                <version>${version.junit.platform}</version>
-                <scope>test</scope>
-            </dependency>
             <dependency>
                 <groupId>org.hamcrest</groupId>
                 <artifactId>hamcrest-all</artifactId>
                 <version>1.3</version>
                 <scope>test</scope>
             </dependency>
-            <dependency>
-                <!-- Specified in case it is needed (though tests run normally without it) -->
-                <groupId>org.junit.platform</groupId>
-                <artifactId>junit-platform-runner</artifactId>
-                <version>${version.junit.platform}</version>
-                <scope>test</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.junit.platform</groupId>
-                <artifactId>junit-platform-surefire-provider</artifactId>
-                <version>1.3.2</version>
-                <scope>test</scope>
-            </dependency>
             <dependency>
                 <groupId>org.mockito</groupId>
                 <artifactId>mockito-core</artifactId>
@@ -367,4 +342,3 @@
         </profile>
     </profiles>
 </project>
-
diff --git a/reflector/pom.xml b/reflector/pom.xml
index b059fe90..50a108d3 100644
--- a/reflector/pom.xml
+++ b/reflector/pom.xml
@@ -2,11 +2,10 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
     <parent>
-        <artifactId>padla</artifactId>
         <groupId>ru.progrm-jarvis</groupId>
-        <version>1.0.0-rc.5</version>
+        <artifactId>padla</artifactId>
+        <version>1.0.0-rc.6</version>
     </parent>
     <artifactId>reflector</artifactId>
 
@@ -26,6 +25,7 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.hamcrest</groupId>
diff --git a/tools/pom.xml b/tools/pom.xml
index 9495387d..f75e10fe 100644
--- a/tools/pom.xml
+++ b/tools/pom.xml
@@ -2,17 +2,16 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
     <parent>
-        <artifactId>padla</artifactId>
         <groupId>ru.progrm-jarvis</groupId>
-        <version>1.0.0-rc.5</version>
+        <artifactId>padla</artifactId>
+        <version>1.0.0-rc.6</version>
     </parent>
     <artifactId>padla-tools</artifactId>
+    <packaging>pom</packaging>
     <modules>
         <module>unsafe-methods-access-generator</module>
     </modules>
-    <packaging>pom</packaging>
 
     <build>
         <defaultGoal>clean package</defaultGoal>
@@ -50,5 +49,4 @@
             </dependency>
         </dependencies>
     </dependencyManagement>
-
 </project>
diff --git a/tools/unsafe-methods-access-generator/pom.xml b/tools/unsafe-methods-access-generator/pom.xml
index 0bb12de8..2262acf7 100644
--- a/tools/unsafe-methods-access-generator/pom.xml
+++ b/tools/unsafe-methods-access-generator/pom.xml
@@ -2,11 +2,10 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
     <parent>
-        <artifactId>padla-tools</artifactId>
         <groupId>ru.progrm-jarvis</groupId>
-        <version>1.0.0-rc.5</version>
+        <artifactId>padla-tools</artifactId>
+        <version>1.0.0-rc.6</version>
     </parent>
     <artifactId>unsafe-methods-access-generator</artifactId>
 
diff --git a/ultimate-messenger/pom.xml b/ultimate-messenger/pom.xml
index 1bc223a4..9019dee0 100644
--- a/ultimate-messenger/pom.xml
+++ b/ultimate-messenger/pom.xml
@@ -2,11 +2,10 @@
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
-
     <parent>
-        <artifactId>padla</artifactId>
         <groupId>ru.progrm-jarvis</groupId>
-        <version>1.0.0-rc.5</version>
+        <artifactId>padla</artifactId>
+        <version>1.0.0-rc.6</version>
     </parent>
     <artifactId>ultimate-messenger</artifactId>
 
@@ -45,10 +44,12 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-params</artifactId>
+            <scope>test</scope>
         </dependency>
         <dependency>
             <groupId>org.hamcrest</groupId>