migrate to gradle

.gitignore

@@ -6,3 +6,7 @@ target
 */.classpath
 */.project
 */.settings
+*/build
+build
+.idea
+.gradle

actions/build.gradle

@@ -0,0 +1,16 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ */
+
+plugins {
+    id 'com.ibm.common.java-conventions'
+}
+
+dependencies {
+    implementation project(':activitystreams-core')
+    implementation 'com.google.code.gson:gson:2.2.4'
+    implementation 'com.google.guava:guava:16.0.1'
+    testImplementation 'junit:junit:4.11'
+}
+
+description = 'Activity Streams 2.0 - Actions'

buildSrc/build.gradle

@@ -0,0 +1,13 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ */
+
+plugins {
+    // Support convention plugins written in Groovy. Convention plugins are build scripts in 'src/main' that automatically become available as plugins in the main build.
+    id 'groovy-gradle-plugin'
+}
+
+repositories {
+    // Use the plugin portal to apply community plugins in convention plugins.
+    gradlePluginPortal()
+}

buildSrc/src/main/groovy/com.ibm.common.java-conventions.gradle

@@ -0,0 +1,31 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ */
+
+plugins {
+    id 'java-library'
+    id 'maven-publish'
+}
+
+repositories {
+    mavenLocal()
+    maven {
+        url = uri('https://repo.maven.apache.org/maven2/')
+    }
+}
+
+group = 'com.ibm.common'
+version = '0.0.1-SNAPSHOT'
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+publishing {
+    publications {
+        maven(MavenPublication) {
+            from(components.java)
+        }
+    }
+}
+
+tasks.withType(JavaCompile) {
+    options.encoding = 'UTF-8'
+}

core/build.gradle

@@ -0,0 +1,16 @@
+/*
+ * This file was generated by the Gradle 'init' task.
+ */
+
+plugins {
+    id 'com.ibm.common.java-conventions'
+}
+
+dependencies {
+    implementation 'com.google.code.gson:gson:2.2.4'
+    implementation 'com.google.guava:guava:16.0.1'
+    implementation 'joda-time:joda-time:2.3'
+    testImplementation 'junit:junit:4.11'
+}
+
+description = 'Activity Streams 2.0 - Core'

core/src/main/java/com/ibm/common/activitystreams/ASObject.java

@@ -1478,22 +1478,6 @@ public B set(String key, Supplier<?> value) {
       }
     }
 
-    /**
-     * Set a property from a given callable
-     * @param key String
-     * @param value Callable<V>
-     * @return B 
-     **/
-    public B set(String key, Callable<?> value) {
-      try {
-        return value == null ?
-          (B)this : 
-          set(key,value.call());
-      } catch (Throwable t) {
-        throw propagate(t);
-      }
-    }
-
     /**
      * Set the scope
      * @param url String