Merge branch '5.2.x'

spring-web/src/main/java/org/springframework/web/cors/reactive/UrlBasedCorsConfigurationSource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -50,7 +50,7 @@ public class UrlBasedCorsConfigurationSource implements CorsConfigurationSource
 	 * @since 5.0.6
 	 */
 	public UrlBasedCorsConfigurationSource() {
-		this(new PathPatternParser());
+		this(PathPatternParser.defaultInstance);
 	}
 
 	/**

spring-web/src/main/java/org/springframework/web/util/pattern/PathPatternParser.java

@@ -112,4 +112,35 @@ public class PathPatternParser {
 		return new InternalPathPatternParser(this).parse(pathPattern);
 	}
 
+
+	/**
+	 * Shared, read-only instance of {@code PathPatternParser}. Uses default settings:
+	 * <ul>
+	 * <li>{@code matchOptionalTrailingSeparator=true}
+	 * <li>{@code caseSensitivetrue}
+	 * <li>{@code pathOptions=PathContainer.Options.HTTP_PATH}
+	 * </ul>
+	 */
+	public final static PathPatternParser defaultInstance = new PathPatternParser() {
+
+		@Override
+		public void setMatchOptionalTrailingSeparator(boolean matchOptionalTrailingSeparator) {
+			raiseError();
+		}
+
+		@Override
+		public void setCaseSensitive(boolean caseSensitive) {
+			raiseError();
+		}
+
+		@Override
+		public void setPathOptions(PathContainer.Options pathOptions) {
+			raiseError();
+		}
+
+		private void raiseError() {
+			throw new UnsupportedOperationException(
+					"This is a read-only, shared instance that cannot be modified");
+		}
+	};
 }