群发消息增加isSendAll属性及相关方法，用于显式指定是否群发消息至所有用户

weixin-java-mp/src/main/java/me/chanjar/weixin/mp/bean/WxMpMassTagMessage.java

@@ -16,6 +16,7 @@ public class WxMpMassTagMessage implements Serializable {
   private String msgType;
   private String content;
   private String mediaId;
+  private boolean isSendAll = false;
   private boolean sendIgnoreReprint = false;
 
   public WxMpMassTagMessage() {
@@ -88,4 +89,18 @@ public class WxMpMassTagMessage implements Serializable {
     this.sendIgnoreReprint = sendIgnoreReprint;
   }
 
+  /**
+   * 是否群发给所有用户
+   */
+  public boolean isSendAll() {
+    return isSendAll;
+  }
+
+  public void setSendAll(boolean sendAll) {
+    if(sendAll){
+      this.tagId = null;
+    }
+
+    isSendAll = sendAll;
+  }
 }

weixin-java-mp/src/main/java/me/chanjar/weixin/mp/util/json/WxMpMassTagMessageGsonAdapter.java

@@ -24,7 +24,7 @@ public class WxMpMassTagMessageGsonAdapter implements JsonSerializer<WxMpMassTag
     JsonObject messageJson = new JsonObject();
 
     JsonObject filter = new JsonObject();
-    if (null == message.getTagId()) {
+    if (message.isSendAll() || null == message.getTagId()) {
       filter.addProperty("is_to_all", true);
     } else {
       filter.addProperty("is_to_all", false);