Polishing.

Fix typos. Add since tag.

See #2078
Original pull request: #2081

spring-data-relational/src/main/java/org/springframework/data/relational/core/conversion/MappingRelationalConverter.java

@@ -44,7 +44,16 @@ import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.PersistentPropertyAccessor;
 import org.springframework.data.mapping.PersistentPropertyPathAccessor;
 import org.springframework.data.mapping.context.MappingContext;
-import org.springframework.data.mapping.model.*;
+import org.springframework.data.mapping.model.CachingValueExpressionEvaluatorFactory;
+import org.springframework.data.mapping.model.ConvertingPropertyAccessor;
+import org.springframework.data.mapping.model.EntityInstantiator;
+import org.springframework.data.mapping.model.ParameterValueProvider;
+import org.springframework.data.mapping.model.PersistentEntityParameterValueProvider;
+import org.springframework.data.mapping.model.PropertyValueProvider;
+import org.springframework.data.mapping.model.SimpleTypeHolder;
+import org.springframework.data.mapping.model.SpELContext;
+import org.springframework.data.mapping.model.ValueExpressionEvaluator;
+import org.springframework.data.mapping.model.ValueExpressionParameterValueProvider;
 import org.springframework.data.projection.EntityProjection;
 import org.springframework.data.projection.EntityProjectionIntrospector;
 import org.springframework.data.projection.EntityProjectionIntrospector.ProjectionPredicate;
@@ -784,16 +793,18 @@ public class MappingRelationalConverter extends AbstractRelationalConverter
 			Class<?> targetComponentType = mapped.get(0).getClass();
 			targetType = Array.newInstance(targetComponentType, 0).getClass();
 		}
+
 		return getConversionService().convert(mapped, targetType);
 	}
 
 	/**
-	 * Unwraps technology specific wrappers. Custom conversions may choose to return a wrapper class that contains additional information for the technology driver.
+	 * Unwraps technology-specific wrappers. Custom conversions may choose to return a wrapper class that contains
-	 * These wrappers can't be used as members of a collection, therefore we may have to unwrap the values.
+	 * additional information for the driver. These wrappers can't be used as members of a collection, therefore we may
-	 *
+	 * have to unwrap the values. This method allows technology-specific implementations to provide such an unwrapping
-	 * This method allows technology specific implemenations to provide such an unwrapping mechanism.
+	 * mechanism.
 	 *
 	 * @param convertedValue a value that might need unwrapping.
+	 * @since 4.0
 	 */
 	@Nullable
 	protected Object unwrap(@Nullable Object convertedValue) {