Support comma-separated basePackage values in EntityScan

See gh-27355

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/domain/EntityScanPackages.java

@@ -30,6 +30,7 @@ import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.GenericBeanDefinition;
+import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
 import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.env.Environment;
@@ -141,7 +142,10 @@ public class EntityScanPackages {
 					.fromMap(metadata.getAnnotationAttributes(EntityScan.class.getName()));
 			Set<String> packagesToScan = new LinkedHashSet<>();
 			for (String basePackage : attributes.getStringArray("basePackages")) {
-				addResolvedPackage(basePackage, packagesToScan);
+				String[] tokenized = StringUtils.tokenizeToStringArray(
+						this.environment.resolvePlaceholders(basePackage),
+						ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
+				Collections.addAll(packagesToScan, tokenized);
 			}
 			for (Class<?> basePackageClass : attributes.getClassArray("basePackageClasses")) {
 				addResolvedPackage(ClassUtils.getPackageName(basePackageClass), packagesToScan);

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/domain/EntityScannerTests.java

@@ -25,6 +25,7 @@ import javax.persistence.Entity;
 import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentCaptor;
 
+import org.springframework.boot.autoconfigure.data.jpa.city.City;
 import org.springframework.boot.autoconfigure.domain.scan.a.EmbeddableA;
 import org.springframework.boot.autoconfigure.domain.scan.a.EntityA;
 import org.springframework.boot.autoconfigure.domain.scan.b.EmbeddableB;
@@ -119,6 +120,20 @@ class EntityScannerTests {
 		assertThat(annotationTypeFilter.getValue().getAnnotationType()).isEqualTo(Entity.class);
 	}
 
+	@Test
+	void scanShouldScanCommaSeparatedPackagesInPlaceholderPackage() throws Exception {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		TestPropertyValues.of(
+				"com.example.entity-package=org.springframework.boot.autoconfigure.domain.scan,org.springframework.boot.autoconfigure.data.jpa.city")
+				.applyTo(context);
+		context.register(ScanPlaceholderConfig.class);
+		context.refresh();
+		EntityScanner scanner = new EntityScanner(context);
+		Set<Class<?>> scanned = scanner.scan(Entity.class);
+		assertThat(scanned).containsOnly(EntityA.class, EntityB.class, EntityC.class, City.class);
+		context.close();
+	}
+
 	private static class TestEntityScanner extends EntityScanner {
 
 		private final ClassPathScanningCandidateComponentProvider candidateComponentProvider;