App Config Spring - Json content type fix

sdk/spring/spring-cloud-azure-appconfiguration-config/CHANGELOG.md

@@ -8,6 +8,8 @@
 
 ### Bugs Fixed
 
+- Fixes a bug where ';' was ignored in JSON content type checking.
+
 ### Other Changes
 
 ## 7.1.0 (2026-03-11)

sdk/spring/spring-cloud-azure-appconfiguration-config/src/main/java/com/azure/spring/cloud/appconfiguration/config/implementation/JsonConfigurationParser.java

@@ -2,10 +2,8 @@
 // Licensed under the MIT License.
 package com.azure.spring.cloud.appconfiguration.config.implementation;
 
-import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Iterator;
-import java.util.List;
 import java.util.Map;
 
 import org.springframework.boot.context.properties.source.InvalidConfigurationPropertyValueException;
@@ -30,21 +28,48 @@ static boolean isJsonContentType(String contentType) {
             return false;
         }
 
-        if (contentType.contains("/")) {
-            String mainType = contentType.split("/")[0];
-            String subType = contentType.split("/")[1];
+        // Remove parameters like "; charset=utf-8" if present, without using regex-based split
+        String cleanContentType;
+        int semicolonIndex = contentType.indexOf(';');
+        if (semicolonIndex >= 0) {
+            cleanContentType = contentType.substring(0, semicolonIndex).trim();
+        } else {
+            cleanContentType = contentType.trim();
+        }
 
-            if (mainType.equalsIgnoreCase(acceptedMainType)) {
-                if (subType.contains("+")) {
-                    List<String> subtypes = Arrays.asList(subType.split("\\+"));
-                    return subtypes.contains(acceptedSubType);
-                } else {
-                    return subType.equalsIgnoreCase(acceptedSubType);
-                }
-            }
+        if (cleanContentType.isEmpty()) {
+            return false;
+        }
+
+        int slashIndex = cleanContentType.indexOf('/');
+        if (slashIndex <= 0 || slashIndex == cleanContentType.length() - 1) {
+            // No slash, slash at start, or no subtype
+            return false;
+        }
+
+        String mainType = cleanContentType.substring(0, slashIndex);
+        String subType = cleanContentType.substring(slashIndex + 1);
+
+        // RFC 7231/6838: tokens cannot contain whitespace
+        // Check for internal whitespace (after initial trim of the whole content type)
+        if (mainType.contains(" ") || mainType.contains("\t") || 
+            subType.contains(" ") || subType.contains("\t")) {
+            return false;
         }
 
-        return false;
+        if (!mainType.equalsIgnoreCase(acceptedMainType) || subType.isEmpty()) {
+            return false;
+        }
+
+        // Handle structured syntax suffixes like "application/vnd.api+json".
+        // According to RFC 6839, the suffix is the part after the last '+'.
+        int plusIndex = subType.lastIndexOf('+');
+        if (plusIndex >= 0 && plusIndex < subType.length() - 1) {
+            String suffix = subType.substring(plusIndex + 1);
+            return suffix.equalsIgnoreCase(acceptedSubType);
+        } else {
+            return subType.equalsIgnoreCase(acceptedSubType);
+        }
     }
 
     static Map<String, Object> parseJsonSetting(ConfigurationSetting setting)

sdk/spring/spring-cloud-azure-appconfiguration-config/src/test/java/com/azure/spring/cloud/appconfiguration/config/implementation/JsonConfigurationParserTest.java

@@ -25,17 +25,77 @@ public class JsonConfigurationParserTest {
 
     @Test
     public void isJsonContentType() {
+        // Basic valid JSON content types
         assertTrue(JsonConfigurationParser.isJsonContentType("application/json"));
         assertTrue(JsonConfigurationParser.isJsonContentType("application/api+json"));
-        assertTrue(JsonConfigurationParser.isJsonContentType("application/json+activity"));
         assertTrue(JsonConfigurationParser.isJsonContentType("application/vnd.xxxx+json"));
         assertTrue(JsonConfigurationParser.isJsonContentType("application/vnd.microsoft.appconfig.document+json"));
+
+        // Invalid content types
         assertFalse(JsonConfigurationParser.isJsonContentType("application"));
         assertFalse(JsonConfigurationParser.isJsonContentType("app/json"));
         assertFalse(JsonConfigurationParser.isJsonContentType("app/config"));
         assertFalse(JsonConfigurationParser.isJsonContentType("application/config"));
         assertFalse(JsonConfigurationParser.isJsonContentType(""));
         assertFalse(JsonConfigurationParser.isJsonContentType(null));
+        assertFalse(JsonConfigurationParser.isJsonContentType("application/json+activity")); // activity is the suffix, not json
+    }
+
+    @Test
+    public void isJsonContentTypeWithParameters() {
+        // Content types with charset and other parameters
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/json; charset=utf-8"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/json;charset=utf-8"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/json ; charset=utf-8"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/vnd.api+json; charset=utf-8"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/json; charset=ISO-8859-1"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/json;boundary=something"));
+    }
+
+    @Test
+    public void isJsonContentTypeWithWhitespace() {
+        // Content types with various whitespace at the boundaries
+        assertTrue(JsonConfigurationParser.isJsonContentType(" application/json"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/json "));
+        assertTrue(JsonConfigurationParser.isJsonContentType(" application/json "));
+
+        // Internal whitespace around '/' or '+' is not allowed by RFC 7231/6838 token rules
+        assertFalse(JsonConfigurationParser.isJsonContentType("application / json"));
+        assertFalse(JsonConfigurationParser.isJsonContentType("application/vnd.api + json"));
+    }
+
+    @Test
+    public void isJsonContentTypeCaseInsensitive() {
+        // Case variations
+        assertTrue(JsonConfigurationParser.isJsonContentType("Application/Json"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("APPLICATION/JSON"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/JSON"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("Application/vnd.api+JSON"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/API+JSON"));
+    }
+
+    @Test
+    public void isJsonContentTypeEdgeCases() {
+        // Edge cases and boundary conditions
+        assertFalse(JsonConfigurationParser.isJsonContentType("application/")); // Empty subtype
+        assertFalse(JsonConfigurationParser.isJsonContentType("/json")); // Empty main type
+        assertFalse(JsonConfigurationParser.isJsonContentType("/")); // Both empty
+        assertFalse(JsonConfigurationParser.isJsonContentType("application/xml"));
+        assertFalse(JsonConfigurationParser.isJsonContentType("text/json")); // Wrong main type
+        assertFalse(JsonConfigurationParser.isJsonContentType("application/json+xml")); // json not as suffix
+        assertFalse(JsonConfigurationParser.isJsonContentType("application/xml+html")); // No json at all
+        assertFalse(JsonConfigurationParser.isJsonContentType("   ")); // Only whitespace
+    }
+
+    @Test
+    public void isJsonContentTypeComplexStructuredSyntax() {
+        // Complex structured syntax suffixes (RFC 6839)
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/problem+json"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/merge-patch+json"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/json-patch+json"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/ld+json")); // JSON-LD
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/hal+json"));
+        assertTrue(JsonConfigurationParser.isJsonContentType("application/vnd.geo+json"));
     }
 
     @Test