Fix issue in MappingJacksonJsonView

Issue: SPR-10752

spring-webmvc/src/main/java/org/springframework/web/servlet/view/json/MappingJackson2JsonView.java

@@ -23,20 +23,21 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
+
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import com.fasterxml.jackson.core.JsonEncoding;
-import com.fasterxml.jackson.core.JsonGenerator;
-import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.databind.SerializationFeature;
-
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.validation.BindingResult;
 import org.springframework.web.servlet.View;
 import org.springframework.web.servlet.view.AbstractView;
 
+import com.fasterxml.jackson.core.JsonEncoding;
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+
 /**
  * Spring MVC {@link View} that renders JSON content by serializing the model for the current request
  * using <a href="http://jackson.codehaus.org/">Jackson 2's</a> {@link ObjectMapper}.
@@ -142,7 +143,7 @@ public class MappingJackson2JsonView extends AbstractView {
 	 * @see #setJsonPrefix
 	 */
 	public void setPrefixJson(boolean prefixJson) {
-		this.jsonPrefix = "{} && ";
+		this.jsonPrefix = prefixJson ? "{} && " : "";
 	}
 
 	/**

spring-webmvc/src/main/java/org/springframework/web/servlet/view/json/MappingJacksonJsonView.java

@@ -23,6 +23,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
+
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
@@ -30,7 +31,6 @@ import org.codehaus.jackson.JsonEncoding;
 import org.codehaus.jackson.JsonGenerator;
 import org.codehaus.jackson.map.ObjectMapper;
 import org.codehaus.jackson.map.SerializationConfig;
-
 import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 import org.springframework.validation.BindingResult;
@@ -142,7 +142,7 @@ public class MappingJacksonJsonView extends AbstractView {
 	 * @see #setJsonPrefix
 	 */
 	public void setPrefixJson(boolean prefixJson) {
-		this.jsonPrefix = "{} && ";
+		this.jsonPrefix = prefixJson ? "{} && " : "";
 	}
 
 	/**