Allow additional build info properties to have provided values

Closes gh-37889

Author: wilkinsona

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/docs/asciidoc/integrating-with-actuator.adoc

@@ -95,3 +95,5 @@ include::../gradle/integrating-with-actuator/build-info-additional.gradle[tags=a
 ----
 include::../gradle/integrating-with-actuator/build-info-additional.gradle.kts[tags=additional]
 ----
+
+An additional property's value can be computed lazily by using a `Provider`.

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/buildinfo/BuildInfoProperties.java

@@ -30,6 +30,7 @@
 import org.gradle.api.Project;
 import org.gradle.api.provider.MapProperty;
 import org.gradle.api.provider.Property;
+import org.gradle.api.provider.Provider;
 import org.gradle.api.provider.SetProperty;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.Internal;
@@ -155,7 +156,12 @@ private <T> T getIfNotExcluded(Property<T> property, String name, Supplier<T> de
 
 	private Map<String, String> coerceToStringValues(Map<String, Object> input) {
 		Map<String, String> output = new HashMap<>();
-		input.forEach((key, value) -> output.put(key, (value != null) ? value.toString() : null));
+		input.forEach((key, value) -> {
+			if (value instanceof Provider<?> provider) {
+				value = provider.getOrNull();
+			}
+			output.put(key, (value != null) ? value.toString() : null);
+		});
 		return output;
 	}
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/dsl/BuildInfoDslIntegrationTests-additionalProperties.gradle

@@ -10,7 +10,8 @@ springBoot {
 	buildInfo {
 		properties {
 			additional = [
-				'a': 'alpha', 'b': 'bravo'
+				'a': 'alpha',
+				'b': providers.provider({'bravo'})
 			]
 		}
 	}