Expect JSON results to be always present

This saves an unnecessary and annoying null dereference check.

acme4j-client/src/main/java/org/shredzone/acme4j/Account.java

@@ -203,10 +203,7 @@ public class Account extends AcmeJsonResource {
             }
 
             Authorization auth = getLogin().bindAuthorization(authLocation);
-            JSON json = conn.readJsonResponse();
+            auth.setJSON(conn.readJsonResponse());
-            if (json != null) {
-                auth.setJSON(json);
-            }
             return auth;
         }
     }
@@ -258,11 +255,7 @@ public class Account extends AcmeJsonResource {
             claims.put(KEY_STATUS, "deactivated");
 
             conn.sendSignedRequest(getLocation(), claims, getLogin());
-
+            setJSON(conn.readJsonResponse());
-            JSON json = conn.readJsonResponse();
-            if (json != null) {
-                setJSON(json);
-            }
         }
     }
 
@@ -348,11 +341,7 @@ public class Account extends AcmeJsonResource {
                 }
 
                 conn.sendSignedRequest(getLocation(), claims, getLogin());
-
+                setJSON(conn.readJsonResponse());
-                JSON json = conn.readJsonResponse();
-                if (json != null) {
-                    setJSON(json);
-                }
             }
         }
     }

acme4j-client/src/main/java/org/shredzone/acme4j/AccountBuilder.java

@@ -30,7 +30,6 @@ import org.shredzone.acme4j.connector.Resource;
 import org.shredzone.acme4j.exception.AcmeException;
 import org.shredzone.acme4j.exception.AcmeProtocolException;
 import org.shredzone.acme4j.toolbox.AcmeUtils;
-import org.shredzone.acme4j.toolbox.JSON;
 import org.shredzone.acme4j.toolbox.JSONBuilder;
 import org.shredzone.acme4j.toolbox.JoseUtils;
 import org.slf4j.Logger;
@@ -219,10 +218,7 @@ public class AccountBuilder {
             }
 
             Login login = new Login(location, keyPair, session);
-            JSON json = conn.readJsonResponse();
+            login.getAccount().setJSON(conn.readJsonResponse());
-            if (json != null) {
-                login.getAccount().setJSON(json);
-            }
             return login;
         }
     }

acme4j-client/src/main/java/org/shredzone/acme4j/AcmeJsonResource.java

@@ -117,10 +117,7 @@ public abstract class AcmeJsonResource extends AcmeResource {
         LOG.debug("update {}", resourceType);
         try (Connection conn = getSession().connect()) {
             conn.sendSignedPostAsGetRequest(getLocation(), getLogin());
-            JSON json = conn.readJsonResponse();
+            setJSON(conn.readJsonResponse());
-            if (json != null) {
-                setJSON(json);
-            }
             conn.handleRetryAfter(resourceType + " is not completed yet");
         }
     }

acme4j-client/src/main/java/org/shredzone/acme4j/Authorization.java

@@ -28,7 +28,6 @@ import org.shredzone.acme4j.connector.Connection;
 import org.shredzone.acme4j.exception.AcmeException;
 import org.shredzone.acme4j.exception.AcmeProtocolException;
 import org.shredzone.acme4j.toolbox.AcmeUtils;
-import org.shredzone.acme4j.toolbox.JSON;
 import org.shredzone.acme4j.toolbox.JSON.Value;
 import org.shredzone.acme4j.toolbox.JSONBuilder;
 import org.slf4j.Logger;
@@ -156,11 +155,7 @@ public class Authorization extends AcmeJsonResource {
             claims.put("status", "deactivated");
 
             conn.sendSignedRequest(getLocation(), claims, getLogin());
-
+            setJSON(conn.readJsonResponse());
-            JSON json = conn.readJsonResponse();
-            if (json != null) {
-                setJSON(json);
-            }
         }
     }
 

acme4j-client/src/main/java/org/shredzone/acme4j/Login.java

@@ -135,9 +135,7 @@ public class Login {
     public Challenge bindChallenge(URL location) throws AcmeException {
         Connection connect = session.connect();
         connect.sendSignedPostAsGetRequest(location, this);
-        JSON data = connect.readJsonResponse();
+        return createChallenge(connect.readJsonResponse());
-        Objects.requireNonNull(data, "data");
-        return createChallenge(data);
     }
 
     /**

acme4j-client/src/main/java/org/shredzone/acme4j/Order.java

@@ -26,7 +26,6 @@ import javax.annotation.ParametersAreNonnullByDefault;
 
 import org.shredzone.acme4j.connector.Connection;
 import org.shredzone.acme4j.exception.AcmeException;
-import org.shredzone.acme4j.toolbox.JSON;
 import org.shredzone.acme4j.toolbox.JSON.Value;
 import org.shredzone.acme4j.toolbox.JSONBuilder;
 import org.slf4j.Logger;
@@ -266,11 +265,7 @@ public class Order extends AcmeJsonResource {
             claims.put("status", "canceled");
 
             conn.sendSignedRequest(getLocation(), claims, getLogin());
-
+            setJSON(conn.readJsonResponse());
-            JSON json = conn.readJsonResponse();
-            if (json != null) {
-                setJSON(json);
-            }
         }
     }
 

acme4j-client/src/main/java/org/shredzone/acme4j/OrderBuilder.java

@@ -29,7 +29,6 @@ import org.shredzone.acme4j.connector.Connection;
 import org.shredzone.acme4j.connector.Resource;
 import org.shredzone.acme4j.exception.AcmeException;
 import org.shredzone.acme4j.exception.AcmeProtocolException;
-import org.shredzone.acme4j.toolbox.JSON;
 import org.shredzone.acme4j.toolbox.JSONBuilder;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -322,10 +321,7 @@ public class OrderBuilder {
             }
 
             Order order = new Order(login, orderLocation);
-            JSON json = conn.readJsonResponse();
+            order.setJSON(conn.readJsonResponse());
-            if (json != null) {
-                order.setJSON(json);
-            }
             return order;
         }
     }

acme4j-client/src/main/java/org/shredzone/acme4j/challenge/Challenge.java

@@ -153,11 +153,7 @@ public class Challenge extends AcmeJsonResource {
             prepareResponse(claims);
 
             conn.sendSignedRequest(getLocation(), claims, getLogin());
-
+            setJSON(conn.readJsonResponse());
-            JSON json = conn.readJsonResponse();
-            if (json != null) {
-                setJSON(json);
-            }
         }
     }
 

acme4j-client/src/main/java/org/shredzone/acme4j/connector/Connection.java

@@ -26,6 +26,7 @@ import javax.annotation.ParametersAreNonnullByDefault;
 import org.shredzone.acme4j.Login;
 import org.shredzone.acme4j.Session;
 import org.shredzone.acme4j.exception.AcmeException;
+import org.shredzone.acme4j.exception.AcmeProtocolException;
 import org.shredzone.acme4j.exception.AcmeRetryAfterException;
 import org.shredzone.acme4j.toolbox.JSON;
 import org.shredzone.acme4j.toolbox.JSONBuilder;
@@ -130,9 +131,10 @@ public interface Connection extends AutoCloseable {
     /**
      * Reads a server response as JSON data.
      *
-     * @return The JSON response, or {@code null} if the server did not provide any data.
+     * @return The JSON response.
+     * @throws AcmeProtocolException
+     *         if the JSON response was empty.
      */
-    @CheckForNull
     JSON readJsonResponse() throws AcmeException;
 
     /**

acme4j-client/src/main/java/org/shredzone/acme4j/connector/DefaultConnection.java

@@ -161,12 +161,11 @@ public class DefaultConnection implements Connection {
     }
 
     @Override
-    @CheckForNull
     public JSON readJsonResponse() throws AcmeException {
         assertConnectionIsOpen();
 
         if (conn.getContentLength() == 0) {
-            return null;
+            throw new AcmeProtocolException("Empty response");
         }
 
         String contentType = AcmeUtils.getContentType(conn.getHeaderField(CONTENT_TYPE_HEADER));
@@ -174,20 +173,19 @@ public class DefaultConnection implements Connection {
             throw new AcmeProtocolException("Unexpected content type: " + contentType);
         }
 
-        JSON result = null;
-
         try {
             InputStream in =
                     conn.getResponseCode() < 400 ? conn.getInputStream() : conn.getErrorStream();
-            if (in != null) {
+            if (in == null) {
-                result = JSON.parse(in);
+                throw new AcmeProtocolException("JSON response is empty");
-                LOG.debug("Result JSON: {}", result.toString());
             }
+
+            JSON result = JSON.parse(in);
+            LOG.debug("Result JSON: {}", result.toString());
+            return result;
         } catch (IOException ex) {
             throw new AcmeNetworkException(ex);
         }
-
-        return result;
     }
 
     @Override
@@ -461,11 +459,7 @@ public class DefaultConnection implements Connection {
                 throw new AcmeException("HTTP " + conn.getResponseCode() + ": " + conn.getResponseMessage());
             }
 
-            JSON problemJson = readJsonResponse();
+            Problem problem = new Problem(readJsonResponse(), conn.getURL());
-            if (problemJson == null) {
-                throw new AcmeProtocolException("Empty problem response");
-            }
-            Problem problem = new Problem(problemJson, conn.getURL());
 
             String error = AcmeUtils.stripErrorPrefix(problem.getType().toString());
 

acme4j-client/src/main/java/org/shredzone/acme4j/connector/ResourceIterator.java

@@ -146,11 +146,7 @@ public class ResourceIterator<T extends AcmeResource> implements Iterator<T> {
         Session session = login.getSession();
         try (Connection conn = session.connect()) {
             conn.sendSignedPostAsGetRequest(nextUrl, login);
-
+            fillUrlList(conn.readJsonResponse());
-            JSON json = conn.readJsonResponse();
-            if (json != null) {
-                fillUrlList(json);
-            }
 
             nextUrl = conn.getLinks("next").stream().findFirst().orElse(null);
         }