Protect against NPE with Option.IGNORE_IMPORTS

Update `ConfigDataEnvironmentContributor` to deal with the fact that
the `properties` instance can be `null`.

Fixes gh-25029

Author: philwebb

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

@@ -223,7 +223,7 @@ public Iterator<ConfigDataEnvironmentContributor> iterator() {
 	ConfigDataEnvironmentContributor withBoundProperties(Binder binder) {
 		UseLegacyConfigProcessingException.throwIfRequested(binder);
 		ConfigDataProperties properties = ConfigDataProperties.get(binder);
-		if (this.configDataOptions.contains(ConfigData.Option.IGNORE_IMPORTS)) {
+		if (properties != null && this.configDataOptions.contains(ConfigData.Option.IGNORE_IMPORTS)) {
 			properties = properties.withoutImports();
 		}
 		return new ConfigDataEnvironmentContributor(Kind.BOUND_IMPORT, this.location, this.resource,

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

@@ -26,6 +26,7 @@
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.cloud.CloudPlatform;
+import org.springframework.boot.context.config.ConfigData.Option;
 import org.springframework.boot.context.config.ConfigDataEnvironmentContributor.ImportPhase;
 import org.springframework.boot.context.config.ConfigDataEnvironmentContributor.Kind;
 import org.springframework.boot.context.properties.bind.Binder;
@@ -334,6 +335,17 @@ void bindWhenHasUseLegacyPropertyThrowsException() {
 				() -> createBoundContributor(null, new ConfigData(Collections.singleton(propertySource)), 0));
 	}
 
+	@Test // gh-25029
+	void withBoundPropertiesWhenIgnoringImportsAndNothingBound() {
+		TestResource resource = new TestResource("a");
+		ConfigData configData = new ConfigData(Collections.singleton(new MockPropertySource()), Option.IGNORE_IMPORTS);
+		ConfigDataEnvironmentContributor contributor = ConfigDataEnvironmentContributor.ofUnboundImport(TEST_LOCATION,
+				resource, false, configData, 0);
+		Binder binder = new Binder(contributor.getConfigurationPropertySource());
+		ConfigDataEnvironmentContributor bound = contributor.withBoundProperties(binder);
+		assertThat(bound).isNotNull();
+	}
+
 	private ConfigDataEnvironmentContributor createBoundContributor(String location) {
 		return createBoundContributor(new TestResource(location),
 				new ConfigData(Collections.singleton(new MockPropertySource())), 0);