Add "Task" and "Error" classes.

src/main/java/eu/openaire/urls_worker/models/Error.java

@@ -0,0 +1,36 @@
+package eu.openaire.urls_worker.models;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+public class Error {
+
+    @JsonProperty("type")
+    String type;
+
+    @JsonProperty("message")
+    String message;
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        type = type;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    @Override
+    public String toString() {
+        return "Error{" +
+                "type='" + type + '\'' +
+                ", message='" + message + '\'' +
+                '}';
+    }
+}

src/main/java/eu/openaire/urls_worker/models/Task.java

@@ -0,0 +1,36 @@
+package eu.openaire.urls_worker.models;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+public class Task {
+
+    @JsonProperty("id")
+    String id;
+
+    @JsonProperty("url")
+    String url;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getUrl() {
+        return url;
+    }
+
+    public void setUrl(String url) {
+        this.url = url;
+    }
+
+    @Override
+    public String toString() {
+        return "Task{" +
+                "id='" + id + '\'' +
+                ", url='" + url + '\'' +
+                '}';
+    }
+}