Fix for Issue #4156 : Single quotes in toJson conversions for EnhancedDocuments are no longer being escaped.

.changes/next-release/bugfix-AWSDynamoDBEnhancedClient-8706d14.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "AWS DynamoDB Enhanced Client",
+    "contributor": "",
+    "description": "Fix for Issue [#4156](https://github.com/aws/aws-sdk-java-v2/issues/4156) : Single quotes in toJson conversions for EnhancedDocuments are no longer being escaped."
+}

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/document/JsonStringFormatHelper.java

@@ -74,9 +74,6 @@ public static String addEscapeCharacters(String input) {
                 case '\"':
                     output.append("\\\""); // double-quote character
                     break;
-                case '\'':
-                    output.append("\\'"); // single-quote character
-                    break;
                 default:
                     output.append(ch);
                     break;

services-custom/dynamodb-enhanced/src/test/java/software/amazon/awssdk/enhanced/dynamodb/document/EnhancedDocumentTest.java

@@ -23,6 +23,8 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static software.amazon.awssdk.enhanced.dynamodb.document.EnhancedDocumentTestData.testDataInstance;
 
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
 import java.math.BigDecimal;
 import java.time.LocalDate;
 import java.util.ArrayList;
@@ -55,6 +57,8 @@ private static Stream<Arguments> escapeDocumentStrings() {
         return Stream.of(
             Arguments.of(String.valueOf(c), "{\"key\":\"\\n\"}")
             , Arguments.of("", "{\"key\":\"\"}")
+            , Arguments.of("\"", "{\"key\":\"\\\"\"}")
+            , Arguments.of("\\", "{\"key\":\"\\\\\"}")
             , Arguments.of(" ", "{\"key\":\" \"}")
             , Arguments.of("\t", "{\"key\":\"\\t\"}")
             , Arguments.of("\n", "{\"key\":\"\\n\"}")
@@ -63,6 +67,13 @@ private static Stream<Arguments> escapeDocumentStrings() {
         );
     }
 
+    private static Stream<Arguments> unEscapeDocumentStrings() {
+        return Stream.of(
+            Arguments.of("'", "{\"key\":\"'\"}"),
+            Arguments.of("'single quote'", "{\"key\":\"'single quote'\"}")
+        );
+    }
+
     @Test
     void enhancedDocumentGetters() {
 
@@ -337,13 +348,27 @@ void invalidKeyNames(String escapingString) {
 
     @ParameterizedTest
     @MethodSource("escapeDocumentStrings")
-    void escapingTheValues(String escapingString, String expectedJson) {
+    void escapingTheValues(String escapingString, String expectedJson) throws JsonProcessingException {
+
+        EnhancedDocument document = EnhancedDocument.builder()
+                                                    .attributeConverterProviders(defaultProvider())
+                                                    .putString("key", escapingString)
+                                                    .build();
+        assertThat(document.toJson()).isEqualTo(expectedJson);
+        assertThat(new ObjectMapper().readTree(document.toJson())).isNotNull();
+    }
+
+    @ParameterizedTest
+    @MethodSource("unEscapeDocumentStrings")
+    void unEscapingTheValues(String escapingString, String expectedJson) throws JsonProcessingException {
 
         EnhancedDocument document = EnhancedDocument.builder()
                                                     .attributeConverterProviders(defaultProvider())
                                                     .putString("key", escapingString)
                                                     .build();
         assertThat(document.toJson()).isEqualTo(expectedJson);
+        assertThat(new ObjectMapper().readTree(document.toJson())).isNotNull();
+
     }
 
     @Test