Fix to ignore empty strings while marshalling list of strings in header field. (#3165)

Author: joviegas

.changes/next-release/bugfix-AWSSDKforJavav2-61bbbf3.json

@@ -0,0 +1,6 @@
+{
+    "category": "AWS SDK for Java v2", 
+    "contributor": "", 
+    "type": "bugfix", 
+    "description": "Fix to ignore empty strings while marshalling list of strings in header field."
+}

core/protocols/aws-json-protocol/src/main/java/software/amazon/awssdk/protocols/json/internal/marshall/HeaderMarshaller.java

@@ -27,6 +27,7 @@
 import software.amazon.awssdk.core.traits.ListTrait;
 import software.amazon.awssdk.protocols.core.ValueToStringConverter;
 import software.amazon.awssdk.utils.BinaryUtils;
+import software.amazon.awssdk.utils.StringUtils;
 
 @SdkInternalApi
 public final class HeaderMarshaller {
@@ -51,13 +52,16 @@ public final class HeaderMarshaller {
         = new SimpleHeaderMarshaller<>(JsonProtocolMarshaller.INSTANT_VALUE_TO_STRING);
 
     public static final JsonMarshaller<List<?>> LIST = (list, context, paramName, sdkField) -> {
-        // Null or empty lists cannot be meaningfully (or safely) represented in an HTTP header message since header-fields must 
+        // Null or empty lists cannot be meaningfully (or safely) represented in an HTTP header message since header-fields must
         // typically have a non-empty field-value. https://datatracker.ietf.org/doc/html/rfc7230#section-3.2
         if (isNullOrEmpty(list)) {
             return;
         }
         SdkField memberFieldInfo = sdkField.getRequiredTrait(ListTrait.class).memberFieldInfo();
         for (Object listValue : list) {
+            if (shouldSkipElement(listValue)) {
+                continue;
+            }
             JsonMarshaller marshaller = context.marshallerRegistry().getMarshaller(MarshallLocation.HEADER, listValue);
             marshaller.marshall(listValue, context, paramName, memberFieldInfo);
         }
@@ -66,6 +70,10 @@ public final class HeaderMarshaller {
     private HeaderMarshaller() {
     }
 
+    private static boolean shouldSkipElement(Object element) {
+        return element instanceof String && StringUtils.isBlank((String) element);
+    }
+
     private static class SimpleHeaderMarshaller<T> implements JsonMarshaller<T> {
 
         private final ValueToStringConverter.ValueToString<T> converter;

core/protocols/aws-xml-protocol/src/main/java/software/amazon/awssdk/protocols/xml/internal/marshall/HeaderMarshaller.java

@@ -25,6 +25,7 @@
 import software.amazon.awssdk.core.protocol.MarshallLocation;
 import software.amazon.awssdk.core.traits.ListTrait;
 import software.amazon.awssdk.protocols.core.ValueToStringConverter;
+import software.amazon.awssdk.utils.StringUtils;
 
 @SdkInternalApi
 public final class HeaderMarshaller {
@@ -78,11 +79,18 @@ public void marshall(List<?> list, XmlMarshallerContext context, String paramNam
             }
             SdkField memberFieldInfo = sdkField.getRequiredTrait(ListTrait.class).memberFieldInfo();
             for (Object listValue : list) {
+                if (shouldSkipElement(listValue)) {
+                    continue;
+                }
                 XmlMarshaller marshaller = context.marshallerRegistry().getMarshaller(MarshallLocation.HEADER, listValue);
                 marshaller.marshall(listValue, context, paramName, memberFieldInfo);
             }
         }
 
+        private boolean shouldSkipElement(Object element) {
+            return element instanceof String && StringUtils.isBlank((String) element);
+        }
+
         @Override
         protected boolean shouldEmit(List list) {
             // Null or empty lists cannot be meaningfully (or safely) represented in an HTTP header message since header-fields

test/protocol-tests-core/src/main/resources/software/amazon/awssdk/protocol/suites/cases/rest-json-input.json

@@ -175,6 +175,69 @@
       }
     }
   },
+  {
+    "description": "ListOfStrings in header is serialized as multi-valued header with commas, quotes and double quotes",
+    "given": {
+      "input": {
+        "ListOfStringsMember": [
+          "listValue1,listValue2",
+          "\"listValueTwo\"",
+          "\"\"",
+          "'listValueThree'"
+        ]
+      }
+    },
+    "when": {
+      "action": "marshall",
+      "operation": "MembersInHeaders"
+    },
+    "then": {
+      "serializedAs": {
+        "uri": "/2016-03-11/membersInHeaders",
+        "headers": {
+          "contains": {
+            "x-amz-string-list": [
+              "listValue1,listValue2",
+              "\"listValueTwo\"",
+              "\"\"",
+              "'listValueThree'"
+            ]
+          }
+        }
+      }
+    }
+  },
+  {
+    "description": "ListOfStrings in header serializes only non empty Strings",
+    "given": {
+      "input": {
+        "ListOfStringsMember": [
+          "listValue1",
+          null,
+          "",
+          "",
+          "listValue6"
+        ]
+      }
+    },
+    "when": {
+      "action": "marshall",
+      "operation": "MembersInHeaders"
+    },
+    "then": {
+      "serializedAs": {
+        "uri": "/2016-03-11/membersInHeaders",
+        "headers": {
+          "contains": {
+            "x-amz-string-list": [
+              "listValue1",
+              "listValue6"
+            ]
+          }
+        }
+      }
+    }
+  },
   {
     "description": "Null string header member is not serialized",
     "given": {

test/protocol-tests-core/src/main/resources/software/amazon/awssdk/protocol/suites/cases/rest-xml-input.json

@@ -507,6 +507,69 @@
         }
       }
     }
+  },
+  {
+    "description": "ListOfStrings in header is serialized as multi-valued header with commas, quotes and double quotes",
+    "given": {
+      "input": {
+        "ListOfStringsMember": [
+          "listValue1,listValue2",
+          "\"listValueTwo\"",
+          "\"\"",
+          "'listValueThree'"
+        ]
+      }
+    },
+    "when": {
+      "action": "marshall",
+      "operation": "MembersInHeaders"
+    },
+    "then": {
+      "serializedAs": {
+        "uri": "/2016-03-11/membersInHeaders",
+        "headers": {
+          "contains": {
+            "x-amz-string-list": [
+              "listValue1,listValue2",
+              "\"listValueTwo\"",
+              "\"\"",
+              "'listValueThree'"
+            ]
+          }
+        }
+      }
+    }
+  },
+  {
+    "description": "ListOfStrings in header serializes only non empty Strings",
+    "given": {
+      "input": {
+        "ListOfStringsMember": [
+          "listValue1",
+          null,
+          "",
+          "",
+          "listValue6"
+        ]
+      }
+    },
+    "when": {
+      "action": "marshall",
+      "operation": "MembersInHeaders"
+    },
+    "then": {
+      "serializedAs": {
+        "uri": "/2016-03-11/membersInHeaders",
+        "headers": {
+          "contains": {
+            "x-amz-string-list": [
+              "listValue1",
+              "listValue6"
+            ]
+          }
+        }
+      }
+    }
   }
   //  TODO this is not possible, payloads can only be structures or blobs. Only S3 utilizes this
   //  {