Log warning when using deprecated EndpointId chars

Update `EndpointId` to log a warning when `-` or `.` are used.

Closes gh-14840

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/EndpointId.java

@@ -16,9 +16,14 @@
 
 package org.springframework.boot.actuate.endpoint;
 
+import java.util.HashSet;
 import java.util.Locale;
+import java.util.Set;
 import java.util.regex.Pattern;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 import org.springframework.util.Assert;
 
 /**
@@ -31,7 +36,13 @@ import org.springframework.util.Assert;
  */
 public final class EndpointId {
 
-	private static final Pattern VALID_CHARS = Pattern.compile("[a-zA-Z0-9\\.\\-]+");
+	private static final Log logger = LogFactory.getLog(EndpointId.class);
+
+	private static Set<String> loggedWarnings = new HashSet<>();
+
+	private static final Pattern VALID_PATTERN = Pattern.compile("[a-zA-Z0-9\\.\\-]+");
+
+	private static final Pattern WARNING_PATTERN = Pattern.compile("[\\.\\-]+");
 
 	private final String value;
 
@@ -41,12 +52,15 @@ public final class EndpointId {
 
 	private EndpointId(String value) {
 		Assert.hasText(value, "Value must not be empty");
-		Assert.isTrue(VALID_CHARS.matcher(value).matches(),
+		Assert.isTrue(VALID_PATTERN.matcher(value).matches(),
 				"Value must only contain valid chars");
 		Assert.isTrue(!Character.isDigit(value.charAt(0)),
 				"Value must not start with a number");
 		Assert.isTrue(!Character.isUpperCase(value.charAt(0)),
 				"Value must not start with an uppercase letter");
+		if (WARNING_PATTERN.matcher(value).find()) {
+			logWarning(value);
+		}
 		this.value = value;
 		this.lowerCaseValue = value.toLowerCase(Locale.ENGLISH);
 		this.lowerCaseAlphaNumeric = getAlphaNumerics(this.lowerCaseValue);
@@ -112,4 +126,15 @@ public final class EndpointId {
 		return new EndpointId(value.replace("-", ""));
 	}
 
+	static void resetLoggedWarnings() {
+		loggedWarnings.clear();
+	}
+
+	private static void logWarning(String value) {
+		if (logger.isWarnEnabled() && loggedWarnings.add(value)) {
+			logger.warn("Endpoint ID '" + value
+					+ "' contains invalid characters, please migrate to a valid format.");
+		}
+	}
+
 }

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/EndpointIdTests.java

@@ -16,8 +16,11 @@
 
 package org.springframework.boot.actuate.endpoint;
 
+import org.junit.Rule;
 import org.junit.Test;
 
+import org.springframework.boot.test.rule.OutputCapture;
+
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
@@ -28,6 +31,9 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  */
 public class EndpointIdTests {
 
+	@Rule
+	public OutputCapture output = new OutputCapture();
+
 	@Test
 	public void ofWhenNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> EndpointId.of(null))
@@ -80,6 +86,14 @@ public class EndpointIdTests {
 		assertThat(endpointId.toString()).isEqualTo("foo-bar");
 	}
 
+	@Test
+	public void ofWhenContainsDeprecatedCharsLogsWarning() {
+		EndpointId.resetLoggedWarnings();
+		EndpointId.of("foo-bar");
+		assertThat(this.output.toString()).contains(
+				"Endpoint ID 'foo-bar' contains invalid characters, please migrate to a valid format");
+	}
+
 	@Test
 	public void equalsAndHashCode() {
 		EndpointId one = EndpointId.of("foobar1");