DATAMONGO-2517 - Fix invalid entity creation for text queries.

Fix a glitch in the MappingMongoConverter that uses the single String argument constructor (since it matches in type and parameter count to the given input string) to falsely instantiate an Entity when it should not.

Original pull request: #857.

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

@@ -1283,9 +1283,12 @@ public class MappingMongoConverter extends AbstractMongoConverter implements App
 		}
 
 		if (conversions.isSimpleType(obj.getClass())) {
-			// Doesn't need conversion
-			return getPotentiallyConvertedSimpleWrite(obj,
-					typeInformation != null ? typeInformation.getType() : Object.class);
+
+			Class<?> conversionTargetType = Object.class;
+			if(typeInformation != null && conversions.isSimpleType(typeInformation.getType())) {
+				conversionTargetType = typeInformation.getType();
+			}
+			return getPotentiallyConvertedSimpleWrite(obj, conversionTargetType);
 		}
 
 		if (obj instanceof List) {

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

@@ -56,6 +56,7 @@ import org.springframework.data.mongodb.core.mapping.TextScore;
 import org.springframework.data.mongodb.core.query.BasicQuery;
 import org.springframework.data.mongodb.core.query.Criteria;
 import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.data.mongodb.core.query.TextQuery;
 
 import com.mongodb.BasicDBObject;
 import com.mongodb.MongoClientSettings;
@@ -987,6 +988,16 @@ public class QueryMapperUnitTests {
 				.isEqualTo(new org.bson.Document("level0.$[some_item].arrayCustomName.$[other_item].nes-ted", "value"));
 	}
 
+	@Test // DATAMONGO-2517
+	public void shouldParseNestedKeywordWithArgumentMatchingTheSourceEntitiesConstructorCorrectly() {
+
+		TextQuery source = new TextQuery("test");
+
+		org.bson.Document target = mapper.getMappedObject(source.getQueryObject(),
+				context.getPersistentEntity(WithSingleStringArgConstructor.class));
+		assertThat(target).isEqualTo(org.bson.Document.parse("{\"$text\" : { \"$search\" : \"test\" }}"));
+	}
+
 	class WithDeepArrayNesting {
 
 		List<WithNestedArray> level0;
@@ -1158,4 +1169,16 @@ public class QueryMapperUnitTests {
 		String id;
 		@Field(targetType = FieldType.OBJECT_ID) String stringAsOid;
 	}
+
+	@Document
+	static class WithSingleStringArgConstructor {
+
+		String value;
+
+		public WithSingleStringArgConstructor() {}
+
+		public WithSingleStringArgConstructor(String value) {
+			this.value = value;
+		}
+	}
 }