Avoid reference to HandlerMethod class in ServerErrorException

This breaks the package dependency cycle between web.server/web.method and makes ServerErrorException more generally applicable. Includes deprecation of the plain reason constructor variant, in favor of providing a Method or MethodParameter context (which MatrixVariableMethodArgumentResolver does now).

spring-web/src/main/java/org/springframework/web/server/ServerErrorException.java

@@ -16,10 +16,11 @@
 
 package org.springframework.web.server;
 
+import java.lang.reflect.Method;
+
 import org.springframework.core.MethodParameter;
 import org.springframework.http.HttpStatus;
 import org.springframework.lang.Nullable;
-import org.springframework.web.method.HandlerMethod;
 
 /**
  * Exception for an {@link HttpStatus#INTERNAL_SERVER_ERROR} that exposes extra
@@ -33,49 +34,41 @@ import org.springframework.web.method.HandlerMethod;
 public class ServerErrorException extends ResponseStatusException {
 
 	@Nullable
-	private final HandlerMethod handlerMethod;
+	private final Method handlerMethod;
 
 	@Nullable
 	private final MethodParameter parameter;
 
 
 	/**
-	 * Constructor with an explanation only.
+	 * Constructor for a 500 error with a reason and an optional cause.
+	 * @since 5.0.5
 	 */
-	public ServerErrorException(String reason) {
-		super(HttpStatus.INTERNAL_SERVER_ERROR, reason, null);
+	public ServerErrorException(String reason, @Nullable Throwable cause) {
+		super(HttpStatus.INTERNAL_SERVER_ERROR, reason, cause);
 		this.handlerMethod = null;
 		this.parameter = null;
 	}
 
 	/**
-	 * Constructor with a reason and root cause.
+	 * Constructor for a 500 error with a handler {@link Method} and an optional cause.
 	 * @since 5.0.5
 	 */
-	public ServerErrorException(String reason, Throwable cause) {
+	public ServerErrorException(String reason, Method handlerMethod, @Nullable Throwable cause) {
 		super(HttpStatus.INTERNAL_SERVER_ERROR, reason, cause);
-		this.handlerMethod = null;
+		this.handlerMethod = handlerMethod;
 		this.parameter = null;
 	}
 
 	/**
-	 * Constructor for a 500 error with a {@link MethodParameter}.
+	 * Constructor for a 500 error with a {@link MethodParameter} and an optional cause.
 	 */
 	public ServerErrorException(String reason, MethodParameter parameter, @Nullable Throwable cause) {
 		super(HttpStatus.INTERNAL_SERVER_ERROR, reason, cause);
-		this.handlerMethod = null;
+		this.handlerMethod = parameter.getMethod();
 		this.parameter = parameter;
 	}
 
-	/**
-	 * Constructor for a 500 error with a root cause.
-	 */
-	public ServerErrorException(String reason, HandlerMethod handlerMethod, @Nullable Throwable cause) {
-		super(HttpStatus.INTERNAL_SERVER_ERROR, reason, cause);
-		this.handlerMethod = handlerMethod;
-		this.parameter = null;
-	}
-
 	/**
 	 * Constructor for a 500 error linked to a specific {@code MethodParameter}.
 	 * @deprecated in favor of {@link #ServerErrorException(String, MethodParameter, Throwable)}
@@ -85,18 +78,29 @@ public class ServerErrorException extends ResponseStatusException {
 		this(reason, parameter, null);
 	}
 
+	/**
+	 * Constructor for a 500 error with a reason only.
+	 * @deprecated in favor of {@link #ServerErrorException(String, Throwable)}
+	 */
+	@Deprecated
+	public ServerErrorException(String reason) {
+		super(HttpStatus.INTERNAL_SERVER_ERROR, reason, null);
+		this.handlerMethod = null;
+		this.parameter = null;
+	}
+
 
 	/**
-	 * Return the controller method associated with the error, if any.
+	 * Return the handler method associated with the error, if any.
 	 * @since 5.0.5
 	 */
 	@Nullable
-	public HandlerMethod getHandlerMethod() {
+	public Method getHandlerMethod() {
 		return this.handlerMethod;
 	}
 
 	/**
-	 * Return the controller method argument associated with this error, if any.
+	 * Return the specific method parameter associated with the error, if any.
 	 */
 	@Nullable
 	public MethodParameter getMethodParameter() {

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/SyncInvocableHandlerMethod.java

@@ -109,7 +109,7 @@ public class SyncInvocableHandlerMethod extends HandlerMethod {
 			Throwable ex = processor.getError();
 			if (ex != null) {
 				throw (ex instanceof ServerErrorException ? (ServerErrorException) ex :
-						new ServerErrorException("Failed to invoke: " + getShortLogMessage(), this, ex));
+						new ServerErrorException("Failed to invoke: " + getShortLogMessage(), getMethod(), ex));
 			}
 			return processor.peek();
 		}

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/MatrixVariableMethodArgumentResolver.java

@@ -98,7 +98,8 @@ public class MatrixVariableMethodArgumentResolver extends AbstractNamedValueSync
 						String paramType = param.getNestedParameterType().getName();
 						throw new ServerErrorException(
 								"Found more than one match for URI path parameter '" + name +
-								"' for parameter type [" + paramType + "]. Use 'pathVar' attribute to disambiguate.");
+								"' for parameter type [" + paramType + "]. Use 'pathVar' attribute to disambiguate.",
+								param, null);
 					}
 					paramValues.addAll(params.get(name));
 					found = true;