Add nexus requirements (#8)

Author: v1v

pom.xml

@@ -14,6 +14,7 @@
     <description>
         Maven extension to observe Maven builds with distributed traces using OpenTelemetry SDK
     </description>
+    <url>https://github.com/elastic/opentelemetry-maven-extension</url>
     <properties>
         <java.level>8</java.level>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
@@ -243,6 +244,25 @@
                 <configuration>
                     <source>8</source>
                 </configuration>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>jar</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <artifactId>maven-source-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>generate-source-jar</id>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>jar-no-fork</goal>
+                        </goals>
+                    </execution>
+                </executions>
             </plugin>
             <plugin>
                 <artifactId>maven-release-plugin</artifactId>
@@ -258,10 +278,18 @@
         </plugins>
         <pluginManagement>
             <plugins>
+                <plugin>
+                    <artifactId>maven-javadoc-plugin</artifactId>
+                    <version>3.2.0</version>
+                </plugin>
                 <plugin>
                     <artifactId>maven-release-plugin</artifactId>
                     <version>2.5.3</version>
                 </plugin>
+                <plugin>
+                    <artifactId>maven-source-plugin</artifactId>
+                    <version>3.2.0</version>
+                </plugin>
                 <plugin>
                     <artifactId>maven-gpg-plugin</artifactId>
                     <version>1.6</version>