Servlet 3 multipart request implements getParameterMap defensively as well

Issue: SPR-11074
(cherry picked from commit c7d1c49)

Author: jhoeller

spring-web/src/main/java/org/springframework/web/multipart/support/DefaultMultipartHttpServletRequest.java

@@ -18,7 +18,7 @@
 
 import java.util.Collections;
 import java.util.Enumeration;
-import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.Map;
 import java.util.Set;
@@ -75,22 +75,6 @@ public DefaultMultipartHttpServletRequest(HttpServletRequest request) {
 	}
 
 
-	@Override
-	public Enumeration<String> getParameterNames() {
-		Map<String, String[]> multipartParameters = getMultipartParameters();
-		if (multipartParameters.isEmpty()) {
-			return super.getParameterNames();
-		}
-
-		Set<String> paramNames = new LinkedHashSet<String>();
-		Enumeration<String> paramEnum = super.getParameterNames();
-		while (paramEnum.hasMoreElements()) {
-			paramNames.add(paramEnum.nextElement());
-		}
-		paramNames.addAll(multipartParameters.keySet());
-		return Collections.enumeration(paramNames);
-	}
-
 	@Override
 	public String getParameter(String name) {
 		String[] values = getMultipartParameters().get(name);
@@ -109,11 +93,32 @@ public String[] getParameterValues(String name) {
 		return super.getParameterValues(name);
 	}
 
+	@Override
+	public Enumeration<String> getParameterNames() {
+		Map<String, String[]> multipartParameters = getMultipartParameters();
+		if (multipartParameters.isEmpty()) {
+			return super.getParameterNames();
+		}
+
+		Set<String> paramNames = new LinkedHashSet<String>();
+		Enumeration<String> paramEnum = super.getParameterNames();
+		while (paramEnum.hasMoreElements()) {
+			paramNames.add(paramEnum.nextElement());
+		}
+		paramNames.addAll(multipartParameters.keySet());
+		return Collections.enumeration(paramNames);
+	}
+
 	@Override
 	public Map<String, String[]> getParameterMap() {
-		Map<String, String[]> paramMap = new HashMap<String, String[]>();
+		Map<String, String[]> multipartParameters = getMultipartParameters();
+		if (multipartParameters.isEmpty()) {
+			return super.getParameterMap();
+		}
+
+		Map<String, String[]> paramMap = new LinkedHashMap<String, String[]>();
 		paramMap.putAll(super.getParameterMap());
-		paramMap.putAll(getMultipartParameters());
+		paramMap.putAll(multipartParameters);
 		return paramMap;
 	}
 

spring-web/src/main/java/org/springframework/web/multipart/support/StandardMultipartHttpServletRequest.java

@@ -23,7 +23,9 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Enumeration;
+import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
+import java.util.Map;
 import java.util.Set;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.Part;
@@ -138,6 +140,8 @@ public Enumeration<String> getParameterNames() {
 			return super.getParameterNames();
 		}
 
+		// Servlet 3.0 getParameterNames() not guaranteed to include multipart form items
+		// (e.g. on WebLogic 12) -> need to merge them here to be on the safe side
 		Set<String> paramNames = new LinkedHashSet<String>();
 		Enumeration<String> paramEnum = super.getParameterNames();
 		while (paramEnum.hasMoreElements()) {
@@ -147,6 +151,27 @@ public Enumeration<String> getParameterNames() {
 		return Collections.enumeration(paramNames);
 	}
 
+	@Override
+	public Map<String, String[]> getParameterMap() {
+		if (this.multipartParameterNames == null) {
+			initializeMultipart();
+		}
+		if (this.multipartParameterNames.isEmpty()) {
+			return super.getParameterMap();
+		}
+
+		// Servlet 3.0 getParameterMap() not guaranteed to include multipart form items
+		// (e.g. on WebLogic 12) -> need to merge them here to be on the safe side
+		Map<String, String[]> paramMap = new LinkedHashMap<String, String[]>();
+		paramMap.putAll(super.getParameterMap());
+		for (String paramName : this.multipartParameterNames) {
+			if (!paramMap.containsKey(paramName)) {
+				paramMap.put(paramName, getParameterValues(paramName));
+			}
+		}
+		return paramMap;
+	}
+
 	@Override
 	public String getMultipartContentType(String paramOrFileName) {
 		try {