Merge pull request #34804 from eydunn

* gh-34804:
  Polish "Fix asymmetry of equals when element has trailing dashes"
  Fix asymmetry of equals when element has trailing dashes

Closes gh-34804

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/ConfigurationPropertyName.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2022 the original author or authors.
+ * Copyright 2012-2023 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.
@@ -406,7 +406,7 @@ private boolean dashIgnoringElementEquals(Elements e1, Elements e2, int i) {
 		int i2 = 0;
 		while (i1 < l1) {
 			if (i2 >= l2) {
-				return false;
+				return remainderIsDashes(e1, i, i1);
 			}
 			char ch1 = e1.charAt(i, i1);
 			char ch2 = e2.charAt(i, i2);
@@ -487,6 +487,21 @@ private boolean remainderIsNotAlphanumeric(Elements elements, int element, int i
 		return true;
 	}
 
+	private boolean remainderIsDashes(Elements elements, int element, int index) {
+		if (elements.getType(element).isIndexed()) {
+			return false;
+		}
+		int length = elements.getLength(element);
+		do {
+			char c = Character.toLowerCase(elements.charAt(element, index++));
+			if (c != '-') {
+				return false;
+			}
+		}
+		while (index < length);
+		return true;
+	}
+
 	@Override
 	public int hashCode() {
 		int hashCode = this.hashCode;

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameTests.java

@@ -693,15 +693,22 @@ void equalsWhenNameStartsTheSameUsingDashedCompare() {
 		assertThat(n2).isNotEqualTo(n1);
 	}
 
-	@Test
-	void equalsWhenAdaptedNameMatchesDueToRemovalOfTrailingCharacters() {
-		// gh-30317
+	@Test // gh-30317
+	void equalsWhenAdaptedNameMatchesDueToRemovalOfTrailingNonUniformCharacters() {
 		ConfigurationPropertyName name1 = ConfigurationPropertyName.of("example.demo");
 		ConfigurationPropertyName name2 = ConfigurationPropertyName.adapt("example.demo$$", '.');
 		assertThat(name1).isEqualTo(name2);
 		assertThat(name2).isEqualTo(name1);
 	}
 
+	@Test // gh-34804
+	void equalsSymmetricWhenNameMatchesDueToIgnoredTrailingDashes() {
+		ConfigurationPropertyName n1 = ConfigurationPropertyName.of("example.demo");
+		ConfigurationPropertyName n2 = ConfigurationPropertyName.of("example.demo--");
+		assertThat(n2).isEqualTo(n1);
+		assertThat(n1).isEqualTo(n2);
+	}
+
 	@Test
 	void isValidWhenValidShouldReturnTrue() {
 		assertThat(ConfigurationPropertyName.isValid("")).isTrue();