Add empty javadoc jar for shaded formatter

Closes gh-151

Author: philwebb

spring-javaformat/spring-javaformat-formatter-shaded/pom.xml

@@ -15,6 +15,22 @@
 	</properties>
 	<build>
 		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-jar-plugin</artifactId>
+				<executions>
+					<execution>
+						<id>empty-javadoc-jar</id>
+						<phase>package</phase>
+						<goals>
+							<goal>jar</goal>
+						</goals>
+						<configuration>
+							<classifier>javadoc</classifier>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
 			<plugin>
 				<groupId>org.codehaus.mojo</groupId>
 				<artifactId>flatten-maven-plugin</artifactId>