Support '.' in endpoint names

Update the `EndpointId` constraints to allow '.' in names.

Closes gh-14773

Author: philwebb

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

@@ -22,25 +22,25 @@
 import org.springframework.util.Assert;
 
 /**
- * An identifier for an actuator endpoint. Endpoint IDs may contain only letters and
- * numbers and must begin with a lower-case letter. Case is ignored when comparing
- * endpoint IDs.
+ * An identifier for an actuator endpoint. Endpoint IDs may contain only letters, numbers
+ * and {@code '.'}. They must begin with a lower-case letter. Case is ignored when
+ * comparing endpoint IDs.
  *
  * @author Phillip Webb
  * @since 2.0.6
  */
 public final class EndpointId {
 
-	private static final Pattern ALPHA_NUMERIC = Pattern.compile("[a-zA-Z0-9]+");
+	private static final Pattern VALID_CHARS = Pattern.compile("[a-zA-Z0-9\\.]+");
 
 	private final String value;
 
 	private final String lowerCaseValue;
 
 	private EndpointId(String value) {
 		Assert.hasText(value, "Value must not be empty");
-		Assert.isTrue(ALPHA_NUMERIC.matcher(value).matches(),
-				"Value must be alpha-numeric");
+		Assert.isTrue(VALID_CHARS.matcher(value).matches(),
+				"Value must be alpha-numeric or '.'");
 		Assert.isTrue(!Character.isDigit(value.charAt(0)),
 				"Value must not start with a number");
 		Assert.isTrue(!Character.isUpperCase(value.charAt(0)),

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

@@ -74,6 +74,14 @@ public void ofWhenStartsWithUppercaseLetterThrowsException() {
 		EndpointId.of("Foo");
 	}
 
+	@Test
+	public void ofWhenContainsDotIsValid() {
+		// Ideally we wouldn't support this but there are existing endpoints using the
+		// pattern. See gh-14773
+		EndpointId endpointId = EndpointId.of("foo.bar");
+		assertThat(endpointId.toString()).isEqualTo("foo.bar");
+	}
+
 	@Test
 	public void equalsAndHashCode() {
 		EndpointId one = EndpointId.of("foobar");