Fix schema generation for encrypted fields that are considered domain entities.

This commit makes sure to consider the encrypted annotation on fields that are considered domain type property values, encrypting the entire object if necessary.

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/MappingMongoJsonSchemaCreator.java

@@ -207,8 +207,9 @@ class MappingMongoJsonSchemaCreator implements MongoJsonSchemaCreator {
 								target.properties(nestedProperties.toArray(new JsonSchemaProperty[0])), required));
 					}
 				}
-				return targetProperties.size() == 1 ? targetProperties.iterator().next()
+				JsonSchemaProperty schemaProperty = targetProperties.size() == 1 ? targetProperties.iterator().next()
 						: JsonSchemaProperty.merged(targetProperties);
+				return applyEncryptionDataIfNecessary(property, schemaProperty);
 			}
 		}
 

spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/schema/IdentifiableJsonSchemaProperty.java

@@ -36,6 +36,7 @@ import org.springframework.data.mongodb.core.schema.TypedJsonSchemaObject.Timest
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.StringUtils;
 
 /**
  * {@link JsonSchemaProperty} implementation.
@@ -1171,7 +1172,9 @@ public class IdentifiableJsonSchemaProperty<T extends JsonSchemaObject> implemen
 				enc.append("bsonType", type.toBsonType().value()); // TODO: no samples with type -> is it bson type all the way?
 			}
 
-			enc.append("algorithm", algorithm);
+			if(StringUtils.hasText(algorithm)) {
+				enc.append("algorithm", algorithm);
+			}
 
 			propertySpecification.append("encrypt", enc);
 

spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MappingMongoJsonSchemaCreatorUnitTests.java

@@ -271,6 +271,17 @@ class MappingMongoJsonSchemaCreatorUnitTests {
 				.containsEntry("properties.value", new Document("type", "string"));
 	}
 
+	@Test // GH-4454
+	void wrapEncryptedEntityTypeLikeProperty() {
+
+		MongoJsonSchema schema = MongoJsonSchemaCreator.create() //
+				.filter(MongoJsonSchemaCreator.encryptedOnly()) // filter non encrypted fields
+				.createSchemaFor(WithEncryptedEntityLikeProperty.class);
+
+		assertThat(schema.schemaDocument()) //
+				.containsEntry("properties.domainTypeValue", Document.parse("{'encrypt': {'bsonType': 'object' } }"));
+	}
+
 	// --> TYPES AND JSON
 
 	// --> ENUM
@@ -684,4 +695,9 @@ class MappingMongoJsonSchemaCreatorUnitTests {
 	static class PropertyClashWithA {
 		Integer aNonEncrypted;
 	}
+
+	@Encrypted(algorithm = "AEAD_AES_256_CBC_HMAC_SHA_512-Deterministic")
+	static class WithEncryptedEntityLikeProperty {
+		@Encrypted SomeDomainType domainTypeValue;
+	}
 }