Better integrate ResponseCookie in CookieLocaleResolver

Improve ResponseCookie to allow an existing instance to be mutated
and also to set the cookie value through the builder. This allows
CookieLocaleResolver to avoid duplicating all the fields of
ResponseCookie and to have only a ResponseCookie field instead.

Closes gh-28779

Author: rstoyanchev

spring-web/src/main/java/org/springframework/http/ResponseCookie.java

@@ -54,7 +54,7 @@ public final class ResponseCookie extends HttpCookie {
 	/**
 	 * Private constructor. See {@link #from(String, String)}.
 	 */
-	private ResponseCookie(String name, String value, Duration maxAge, @Nullable String domain,
+	private ResponseCookie(String name, @Nullable String value, Duration maxAge, @Nullable String domain,
 			@Nullable String path, boolean secure, boolean httpOnly, @Nullable String sameSite) {
 
 		super(name, value);
@@ -128,6 +128,19 @@ public String getSameSite() {
 		return this.sameSite;
 	}
 
+	/**
+	 * Return a builder pre-populated with values from {@code "this"} instance.
+	 * @since 6.0
+	 */
+	public ResponseCookieBuilder mutate() {
+		return new DefaultResponseCookieBuilder(getName(), getValue(), false)
+				.maxAge(this.maxAge)
+				.domain(this.domain)
+				.path(this.path)
+				.secure(this.secure)
+				.httpOnly(this.httpOnly)
+				.sameSite(this.sameSite);
+	}
 
 	@Override
 	public boolean equals(@Nullable Object other) {
@@ -179,6 +192,18 @@ public String toString() {
 	}
 
 
+	/**
+	 * Factory method to obtain a builder for a server-defined cookie, given its
+	 * name only, and where the value as well as other attributes can be set
+	 * later via builder methods.
+	 * @param name the cookie name
+	 * @return a builder to create the cookie with
+	 * @since 6.0
+	 */
+	public static ResponseCookieBuilder from(final String name) {
+		return new DefaultResponseCookieBuilder(name, null, false);
+	}
+
 	/**
 	 * Factory method to obtain a builder for a server-defined cookie that starts
 	 * with a name-value pair and may also include attributes.
@@ -187,7 +212,7 @@ public String toString() {
 	 * @return a builder to create the cookie with
 	 */
 	public static ResponseCookieBuilder from(final String name, final String value) {
-		return from(name, value, false);
+		return new DefaultResponseCookieBuilder(name, value, false);
 	}
 
 	/**
@@ -201,90 +226,7 @@ public static ResponseCookieBuilder from(final String name, final String value)
 	 * @since 5.2.5
 	 */
 	public static ResponseCookieBuilder fromClientResponse(final String name, final String value) {
-		return from(name, value, true);
-	}
-
-
-	private static ResponseCookieBuilder from(final String name, final String value, boolean lenient) {
-
-		return new ResponseCookieBuilder() {
-
-			private Duration maxAge = Duration.ofSeconds(-1);
-
-			@Nullable
-			private String domain;
-
-			@Nullable
-			private String path;
-
-			private boolean secure;
-
-			private boolean httpOnly;
-
-			@Nullable
-			private String sameSite;
-
-			@Override
-			public ResponseCookieBuilder maxAge(Duration maxAge) {
-				this.maxAge = maxAge;
-				return this;
-			}
-
-			@Override
-			public ResponseCookieBuilder maxAge(long maxAgeSeconds) {
-				this.maxAge = maxAgeSeconds >= 0 ? Duration.ofSeconds(maxAgeSeconds) : Duration.ofSeconds(-1);
-				return this;
-			}
-
-			@Override
-			public ResponseCookieBuilder domain(@Nullable String domain) {
-				this.domain = initDomain(domain);
-				return this;
-			}
-
-			@Nullable
-			private String initDomain(@Nullable String domain) {
-				if (lenient && StringUtils.hasLength(domain)) {
-					String str = domain.trim();
-					if (str.startsWith("\"") && str.endsWith("\"")) {
-						if (str.substring(1, str.length() - 1).trim().isEmpty()) {
-							return null;
-						}
-					}
-				}
-				return domain;
-			}
-
-			@Override
-			public ResponseCookieBuilder path(@Nullable String path) {
-				this.path = path;
-				return this;
-			}
-
-			@Override
-			public ResponseCookieBuilder secure(boolean secure) {
-				this.secure = secure;
-				return this;
-			}
-
-			@Override
-			public ResponseCookieBuilder httpOnly(boolean httpOnly) {
-				this.httpOnly = httpOnly;
-				return this;
-			}
-
-			@Override
-			public ResponseCookieBuilder sameSite(@Nullable String sameSite) {
-				this.sameSite = sameSite;
-				return this;
-			}
-
-			@Override
-			public ResponseCookie build() {
-				return new ResponseCookie(name, value, this.maxAge, this.domain, this.path,
-						this.secure, this.httpOnly, this.sameSite);
-			}
-		};
+		return new DefaultResponseCookieBuilder(name, value, true);
 	}
 
 
@@ -293,6 +235,12 @@ public ResponseCookie build() {
 	 */
 	public interface ResponseCookieBuilder {
 
+		/**
+		 * Set the cookie value.
+		 * @since 6.0
+		 */
+		ResponseCookieBuilder value(@Nullable String value);
+
 		/**
 		 * Set the cookie "Max-Age" attribute.
 		 *
@@ -429,4 +377,106 @@ public static void validatePath(@Nullable String path) {
 		}
 	}
 
+
+	/**
+	 * Default implementation of {@link ResponseCookieBuilder}.
+	 */
+	private static class DefaultResponseCookieBuilder implements ResponseCookieBuilder {
+
+		private final String name;
+
+		@Nullable
+		private String value;
+
+		private final boolean lenient;
+
+		private Duration maxAge = Duration.ofSeconds(-1);
+
+		@Nullable
+		private String domain;
+
+		@Nullable
+		private String path;
+
+		private boolean secure;
+
+		private boolean httpOnly;
+
+		@Nullable
+		private String sameSite;
+
+		public DefaultResponseCookieBuilder(String name, @Nullable String value, boolean lenient) {
+			this.name = name;
+			this.value = value;
+			this.lenient = lenient;
+		}
+
+		@Override
+		public ResponseCookieBuilder value(@Nullable String value) {
+			this.value = value;
+			return this;
+		}
+
+		@Override
+		public ResponseCookieBuilder maxAge(Duration maxAge) {
+			this.maxAge = maxAge;
+			return this;
+		}
+
+		@Override
+		public ResponseCookieBuilder maxAge(long maxAgeSeconds) {
+			this.maxAge = (maxAgeSeconds >= 0 ? Duration.ofSeconds(maxAgeSeconds) : Duration.ofSeconds(-1));
+			return this;
+		}
+
+		@Override
+		public ResponseCookieBuilder domain(@Nullable String domain) {
+			this.domain = initDomain(domain);
+			return this;
+		}
+
+		@Nullable
+		private String initDomain(@Nullable String domain) {
+			if (this.lenient && StringUtils.hasLength(domain)) {
+				String str = domain.trim();
+				if (str.startsWith("\"") && str.endsWith("\"")) {
+					if (str.substring(1, str.length() - 1).trim().isEmpty()) {
+						return null;
+					}
+				}
+			}
+			return domain;
+		}
+
+		@Override
+		public ResponseCookieBuilder path(@Nullable String path) {
+			this.path = path;
+			return this;
+		}
+
+		@Override
+		public ResponseCookieBuilder secure(boolean secure) {
+			this.secure = secure;
+			return this;
+		}
+
+		@Override
+		public ResponseCookieBuilder httpOnly(boolean httpOnly) {
+			this.httpOnly = httpOnly;
+			return this;
+		}
+
+		@Override
+		public ResponseCookieBuilder sameSite(@Nullable String sameSite) {
+			this.sameSite = sameSite;
+			return this;
+		}
+
+		@Override
+		public ResponseCookie build() {
+			return new ResponseCookie(this.name, this.value, this.maxAge,
+					this.domain, this.path, this.secure, this.httpOnly, this.sameSite);
+		}
+	}
+
 }