Merge pull request #21394 from dreis2211

* pr/21394:
  Polish "Calculate hashCode only once in ConfigurationPropertyName"
  Calculate hashCode only once in ConfigurationPropertyName

Closes gh-21394

Author: snicoll

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

@@ -444,6 +444,7 @@ public int hashCode() {
 				}
 				hashCode = 31 * hashCode + elementHashCode;
 			}
+			this.hashCode = hashCode;
 		}
 		return hashCode;
 	}

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

@@ -619,4 +619,11 @@ void isValidWhenNotValidShouldReturnFalse() {
 		assertThat(ConfigurationPropertyName.isValid("foo!bar")).isFalse();
 	}
 
+	@Test
+	void hashCodeIsStored() {
+		ConfigurationPropertyName name = ConfigurationPropertyName.of("hash.code");
+		int hashCode = name.hashCode();
+		assertThat(name).hasFieldOrPropertyWithValue("hashCode", hashCode);
+	}
+
 }