Add RSocketProtocolException in top-level package

Replaces (now deprecated) RSocketException from the exceptions package
which can lead to cycles (e.g. with frame package).

Other minor refinements:

- error code validation
- shared errorCode() implementation
- error code in toString()
- avoid NPE for null message, it's better to keep the original exception
  and null is allowed by getMessage().

Author: rstoyanchev

rsocket-core/src/main/java/io/rsocket/RSocketProtocolException.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2015-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.rsocket;
+
+import reactor.util.annotation.Nullable;
+
+/**
+ * Exception that represents an RSocket protocol error.
+ *
+ * @see <a href="https://github.com/rsocket/rsocket/blob/master/Protocol.md#error-frame-0x0b">ERROR
+ *     Frame (0x0B)</a>
+ */
+public class RSocketProtocolException extends RuntimeException {
+
+  private static final long serialVersionUID = -1628781753426267554L;
+
+  private final int errorCode;
+
+  /**
+   * Constructor with a protocol error code and a message.
+   *
+   * @param errorCode the RSocket protocol error code
+   * @param message error explanation
+   */
+  public RSocketProtocolException(int errorCode, String message) {
+    this(errorCode, message, null);
+  }
+
+  /**
+   * Alternative to {@link #RSocketProtocolException(int, String)} with a root cause.
+   *
+   * @param errorCode the RSocket protocol error code
+   * @param message error explanation
+   * @param cause a root cause for the error
+   */
+  public RSocketProtocolException(int errorCode, String message, @Nullable Throwable cause) {
+    super(message, cause);
+    this.errorCode = errorCode;
+
+    // Avoid dependency on frame package
+    if (errorCode > 0xFFFFFFFE && errorCode < 0x00000001) {
+      throw new IllegalArgumentException(
+          "Allowed errorCode value should be in range [0x00000001-0xFFFFFFFE]", this);
+    }
+  }
+
+  /**
+   * Return the RSocket <a
+   * href="https://github.com/rsocket/rsocket/blob/master/Protocol.md#error-codes">error code</a>
+   * represented by this exception
+   *
+   * @return the RSocket protocol error code
+   */
+  public int errorCode() {
+    return errorCode;
+  }
+
+  @Override
+  public String toString() {
+    return getClass().getSimpleName()
+        + " (0x"
+        + Integer.toHexString(errorCode)
+        + "): "
+        + getMessage();
+  }
+}

rsocket-core/src/main/java/io/rsocket/exceptions/ApplicationErrorException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.rsocket.exceptions;
 
 import io.rsocket.frame.ErrorType;
+import javax.annotation.Nullable;
 
 /**
  * Application layer logic generating a Reactive Streams {@code onError} event.
@@ -32,25 +33,18 @@ public final class ApplicationErrorException extends RSocketException {
    * Constructs a new exception with the specified message.
    *
    * @param message the message
-   * @throws NullPointerException if {@code message} is {@code null}
    */
   public ApplicationErrorException(String message) {
-    super(message);
+    this(message, null);
   }
 
   /**
    * Constructs a new exception with the specified message and cause.
    *
    * @param message the message
    * @param cause the cause of this exception
-   * @throws NullPointerException if {@code message} or {@code cause} is {@code null}
    */
-  public ApplicationErrorException(String message, Throwable cause) {
-    super(message, cause);
-  }
-
-  @Override
-  public int errorCode() {
-    return ErrorType.APPLICATION_ERROR;
+  public ApplicationErrorException(String message, @Nullable Throwable cause) {
+    super(ErrorType.APPLICATION_ERROR, message, cause);
   }
 }

rsocket-core/src/main/java/io/rsocket/exceptions/CanceledException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.rsocket.exceptions;
 
 import io.rsocket.frame.ErrorType;
+import javax.annotation.Nullable;
 
 /**
  * The Responder canceled the request but may have started processing it (similar to REJECTED but
@@ -33,25 +34,18 @@ public final class CanceledException extends RSocketException {
    * Constructs a new exception with the specified message.
    *
    * @param message the message
-   * @throws NullPointerException if {@code message} is {@code null}
    */
   public CanceledException(String message) {
-    super(message);
+    this(message, null);
   }
 
   /**
    * Constructs a new exception with the specified message and cause.
    *
    * @param message the message
    * @param cause the cause of this exception
-   * @throws NullPointerException if {@code message} or {@code cause} is {@code null}
    */
-  public CanceledException(String message, Throwable cause) {
-    super(message, cause);
-  }
-
-  @Override
-  public int errorCode() {
-    return ErrorType.CANCELED;
+  public CanceledException(String message, @Nullable Throwable cause) {
+    super(ErrorType.CANCELED, message, cause);
   }
 }

rsocket-core/src/main/java/io/rsocket/exceptions/ConnectionCloseException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.rsocket.exceptions;
 
 import io.rsocket.frame.ErrorType;
+import javax.annotation.Nullable;
 
 /**
  * The connection is being terminated. Sender or Receiver of this frame MUST wait for outstanding
@@ -33,25 +34,18 @@ public final class ConnectionCloseException extends RSocketException {
    * Constructs a new exception with the specified message.
    *
    * @param message the message
-   * @throws NullPointerException if {@code message} is {@code null}
    */
   public ConnectionCloseException(String message) {
-    super(message);
+    this(message, null);
   }
 
   /**
    * Constructs a new exception with the specified message and cause.
    *
    * @param message the message
    * @param cause the cause of this exception
-   * @throws NullPointerException if {@code message} or {@code cause} is {@code null}
    */
-  public ConnectionCloseException(String message, Throwable cause) {
-    super(message, cause);
-  }
-
-  @Override
-  public int errorCode() {
-    return ErrorType.CONNECTION_CLOSE;
+  public ConnectionCloseException(String message, @Nullable Throwable cause) {
+    super(ErrorType.CONNECTION_CLOSE, message, cause);
   }
 }

rsocket-core/src/main/java/io/rsocket/exceptions/ConnectionErrorException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.rsocket.exceptions;
 
 import io.rsocket.frame.ErrorType;
+import javax.annotation.Nullable;
 
 /**
  * The connection is being terminated. Sender or Receiver of this frame MAY close the connection
@@ -33,25 +34,18 @@ public final class ConnectionErrorException extends RSocketException implements
    * Constructs a new exception with the specified message.
    *
    * @param message the message
-   * @throws NullPointerException if {@code message} is {@code null}
    */
   public ConnectionErrorException(String message) {
-    super(message);
+    this(message, null);
   }
 
   /**
    * Constructs a new exception with the specified message and cause.
    *
    * @param message the message
    * @param cause the cause of this exception
-   * @throws NullPointerException if {@code message} or {@code cause} is {@code null}
    */
-  public ConnectionErrorException(String message, Throwable cause) {
-    super(message, cause);
-  }
-
-  @Override
-  public int errorCode() {
-    return ErrorType.CONNECTION_ERROR;
+  public ConnectionErrorException(String message, @Nullable Throwable cause) {
+    super(ErrorType.CONNECTION_ERROR, message, cause);
   }
 }

rsocket-core/src/main/java/io/rsocket/exceptions/CustomRSocketException.java

@@ -1,28 +1,36 @@
+/*
+ * Copyright 2015-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package io.rsocket.exceptions;
 
 import io.rsocket.frame.ErrorType;
+import javax.annotation.Nullable;
 
 public class CustomRSocketException extends RSocketException {
   private static final long serialVersionUID = 7873267740343446585L;
 
-  private final int errorCode;
-
   /**
    * Constructs a new exception with the specified message.
    *
    * @param errorCode customizable error code. Should be in range [0x00000301-0xFFFFFFFE]
    * @param message the message
-   * @throws NullPointerException if {@code message} is {@code null}
    * @throws IllegalArgumentException if {@code errorCode} is out of allowed range
    */
   public CustomRSocketException(int errorCode, String message) {
-    super(message);
-    if (errorCode > ErrorType.MAX_USER_ALLOWED_ERROR_CODE
-        && errorCode < ErrorType.MIN_USER_ALLOWED_ERROR_CODE) {
-      throw new IllegalArgumentException(
-          "Allowed errorCode value should be in range [0x00000301-0xFFFFFFFE]");
-    }
-    this.errorCode = errorCode;
+    this(errorCode, message, null);
   }
 
   /**
@@ -31,21 +39,14 @@ public CustomRSocketException(int errorCode, String message) {
    * @param errorCode customizable error code. Should be in range [0x00000301-0xFFFFFFFE]
    * @param message the message
    * @param cause the cause of this exception
-   * @throws NullPointerException if {@code message} or {@code cause} is {@code null}
    * @throws IllegalArgumentException if {@code errorCode} is out of allowed range
    */
-  public CustomRSocketException(int errorCode, String message, Throwable cause) {
-    super(message, cause);
+  public CustomRSocketException(int errorCode, String message, @Nullable Throwable cause) {
+    super(errorCode, message, cause);
     if (errorCode > ErrorType.MAX_USER_ALLOWED_ERROR_CODE
         && errorCode < ErrorType.MIN_USER_ALLOWED_ERROR_CODE) {
       throw new IllegalArgumentException(
-          "Allowed errorCode value should be in range [0x00000301-0xFFFFFFFE]");
+          "Allowed errorCode value should be in range [0x00000301-0xFFFFFFFE]", this);
     }
-    this.errorCode = errorCode;
-  }
-
-  @Override
-  public int errorCode() {
-    return errorCode;
   }
 }

rsocket-core/src/main/java/io/rsocket/exceptions/Exceptions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2018 the original author or authors.
+ * Copyright 2015-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,7 +16,18 @@
 
 package io.rsocket.exceptions;
 
-import static io.rsocket.frame.ErrorFrameFlyweight.*;
+import static io.rsocket.frame.ErrorFrameFlyweight.APPLICATION_ERROR;
+import static io.rsocket.frame.ErrorFrameFlyweight.CANCELED;
+import static io.rsocket.frame.ErrorFrameFlyweight.CONNECTION_CLOSE;
+import static io.rsocket.frame.ErrorFrameFlyweight.CONNECTION_ERROR;
+import static io.rsocket.frame.ErrorFrameFlyweight.INVALID;
+import static io.rsocket.frame.ErrorFrameFlyweight.INVALID_SETUP;
+import static io.rsocket.frame.ErrorFrameFlyweight.MAX_USER_ALLOWED_ERROR_CODE;
+import static io.rsocket.frame.ErrorFrameFlyweight.MIN_USER_ALLOWED_ERROR_CODE;
+import static io.rsocket.frame.ErrorFrameFlyweight.REJECTED;
+import static io.rsocket.frame.ErrorFrameFlyweight.REJECTED_RESUME;
+import static io.rsocket.frame.ErrorFrameFlyweight.REJECTED_SETUP;
+import static io.rsocket.frame.ErrorFrameFlyweight.UNSUPPORTED_SETUP;
 
 import io.netty.buffer.ByteBuf;
 import io.rsocket.frame.ErrorFrameFlyweight;
@@ -28,10 +39,11 @@ public final class Exceptions {
   private Exceptions() {}
 
   /**
-   * Create a {@link RSocketException} from a Frame that matches the error code it contains.
+   * Create a {@link io.rsocket.RSocketProtocolException} from a Frame that matches the error code
+   * it contains.
    *
    * @param frame the frame to retrieve the error code and message from
-   * @return a {@link RSocketException} that matches the error code in the Frame
+   * @return a {@link io.rsocket.RSocketProtocolException} that matches the error code in the Frame
    * @throws NullPointerException if {@code frame} is {@code null}
    */
   public static RuntimeException from(int streamId, ByteBuf frame) {