added compile deps

build.gradle

@@ -24,6 +24,7 @@ buildscript {
 
 apply plugin: "catkin"
 apply plugin: "maven-publish"
+apply plugin: "java-library"
 
 allprojects {
   group 'org.ros.rosjava_core'
@@ -47,7 +48,6 @@ subprojects {
     apply plugin: "osgi"
     apply plugin: "idea"
     apply plugin: "eclipse"
-    apply plugin: "java-library"
   }
 }
 
@@ -58,6 +58,9 @@ repositories {
 
 dependencies {
 
+    // https://mvnrepository.com/artifact/com.google.guava/guava
+    api group: 'com.google.guava', name: 'guava', version: '31.0.1-jre'
+
     // https://mvnrepository.com/artifact/org.jboss.netty/netty
     api group: 'org.jboss.netty', name: 'netty', version: '3.2.10.Final'