Add StandardConfigDataResource.getProfile method

Add a `StandardConfigDataResource.getProfile()` method so that it's
possible to tell the profile used when reading a profile specific
resource.

Fixes gh-25940

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/StandardConfigDataReference.java

@@ -74,6 +74,10 @@ class StandardConfigDataReference {
 		return this.directory;
 	}
 
+	String getProfile() {
+		return this.profile;
+	}
+
 	boolean isSkippable() {
 		return this.configDataLocation.isOptional() || this.directory != null || this.profile != null;
 	}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/StandardConfigDataResource.java

@@ -74,6 +74,15 @@ public class StandardConfigDataResource extends ConfigDataResource {
 		return this.resource;
 	}
 
+	/**
+	 * Return the profile or {@code null} if the resource is not profile specific.
+	 * @return the profile or {@code null}
+	 * @since 2.4.6
+	 */
+	public String getProfile() {
+		return this.reference.getProfile();
+	}
+
 	boolean isEmptyDirectory() {
 		return this.emptyDirectory;
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentPostProcessorTests.java

@@ -127,6 +127,13 @@ class ConfigDataEnvironmentPostProcessorTests {
 		assertThat(this.environment.getActiveProfiles()).containsExactly("dev");
 		assertThat(listener.getAddedPropertySources()).hasSizeGreaterThan(0);
 		assertThat(listener.getProfiles().getActive()).containsExactly("dev");
+		assertThat(listener.getAddedPropertySources().stream().anyMatch((added) -> hasDevProfile(added.getResource())))
+				.isTrue();
+	}
+
+	private boolean hasDevProfile(ConfigDataResource resource) {
+		return (resource instanceof StandardConfigDataResource)
+				&& "dev".equals(((StandardConfigDataResource) resource).getProfile());
 	}
 
 }