Consider projections without input properties open ones.

Closes #3164

Author: mp911de

src/main/java/org/springframework/data/projection/DefaultProjectionInformation.java

@@ -85,7 +85,7 @@ public List<PropertyDescriptor> getInputProperties() {
 
 	@Override
 	public boolean isClosed() {
-		return this.properties.equals(getInputProperties());
+		return hasInputProperties() && this.properties.equals(getInputProperties());
 	}
 
 	/**

src/main/java/org/springframework/data/projection/ProjectionInformation.java

@@ -18,6 +18,8 @@
 import java.beans.PropertyDescriptor;
 import java.util.List;
 
+import org.springframework.util.CollectionUtils;
+
 /**
  * Information about a projection type.
  *
@@ -40,6 +42,17 @@ public interface ProjectionInformation {
 	 */
 	List<PropertyDescriptor> getInputProperties();
 
+	/**
+	 * Returns whether the projection has input properties. Projections without input types are typically open projections
+	 * that do not follow Java's property accessor naming.
+	 *
+	 * @return
+	 * @since 3.3.5
+	 */
+	default boolean hasInputProperties() {
+		return !CollectionUtils.isEmpty(getInputProperties());
+	}
+
 	/**
 	 * Returns whether supplying values for the properties returned via {@link #getInputProperties()} is sufficient to
 	 * create a working proxy instance. This will usually be used to determine whether the projection uses any dynamically

src/main/java/org/springframework/data/repository/query/ReturnedType.java

@@ -33,6 +33,7 @@
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.ConcurrentReferenceHashMap;
 import org.springframework.util.ObjectUtils;
 
@@ -130,9 +131,21 @@ public final boolean isInstance(@Nullable Object source) {
 	 * Returns the properties required to be used to populate the result.
 	 *
 	 * @return
+	 * @see ProjectionInformation#getInputProperties()
 	 */
 	public abstract List<String> getInputProperties();
 
+	/**
+	 * Returns whether the returned type has input properties.
+	 *
+	 * @return
+	 * @since 3.3.5
+	 * @see ProjectionInformation#hasInputProperties()
+	 */
+	public boolean hasInputProperties() {
+		return !CollectionUtils.isEmpty(getInputProperties());
+	}
+
 	/**
 	 * A {@link ReturnedType} that's backed by an interface.
 	 *

src/test/java/org/springframework/data/projection/ProxyProjectionFactoryUnitTests.java

@@ -31,6 +31,7 @@
 import org.springframework.aop.Advisor;
 import org.springframework.aop.TargetClassAware;
 import org.springframework.aop.framework.Advised;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.test.util.ReflectionTestUtils;
 
 /**
@@ -135,6 +136,19 @@ void returnsAllPropertiesAsInputProperties() {
 		var result = projectionInformation.getInputProperties();
 
 		assertThat(result).hasSize(6);
+		assertThat(projectionInformation.hasInputProperties()).isTrue();
+		assertThat(projectionInformation.isClosed()).isTrue();
+	}
+
+	@Test // DATACMNS-630
+	void identifiersOpenProjectionCorrectly() {
+
+		var projectionInformation = factory.getProjectionInformation(OpenProjection.class);
+		var result = projectionInformation.getInputProperties();
+
+		assertThat(result).isEmpty();
+		assertThat(projectionInformation.hasInputProperties()).isFalse();
+		assertThat(projectionInformation.isClosed()).isFalse();
 	}
 
 	@Test // DATACMNS-655, GH-2831
@@ -357,6 +371,12 @@ interface CustomerExcerpt {
 		Map<String, Object> getData();
 	}
 
+	interface OpenProjection {
+
+		@Value("#{@greetingsFrom.groot(target.firstname)}")
+		String hello();
+	}
+
 	interface CustomerExcerptWithDefaultMethod extends CustomerExcerpt {
 
 		default String getFirstnameAndId() {