fix: guard Optional.get() in delete, close FileReader, guard empty form-encode

- VaultController.delete: replace unguarded getRecordIdResponse().get() with
  .orElse(Collections.emptyList()) so an absent field in the API response
  returns an empty list instead of throwing NoSuchElementException (M2)
- BearerToken, SignedDataTokens: wrap FileReader in try/finally to guarantee
  close() is called even when JsonParser throws JsonSyntaxException; close
  IOException is intentionally swallowed since the parse already completed (M3)
- HttpUtility.formatJsonToFormEncodedString: guard against empty entry set so
  substring(0, -1) is not called on an empty StringBuilder (M4)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Devesh-Skyflow

src/main/java/com/skyflow/serviceaccount/util/BearerToken.java

@@ -20,6 +20,7 @@
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
+import java.io.IOException;
 import java.net.MalformedURLException;
 import java.security.PrivateKey;
 import java.util.ArrayList;
@@ -58,8 +59,12 @@ private static V1GetAuthTokenResponse generateBearerTokenFromCredentials(
                 throw new SkyflowException(ErrorCode.INVALID_INPUT.getCode(), ErrorMessage.InvalidCredentials.getMessage());
             }
             FileReader reader = new FileReader(String.valueOf(credentialsFile));
-            JsonObject serviceAccountCredentials = JsonParser.parseReader(reader).getAsJsonObject();
-            return getBearerTokenFromCredentials(serviceAccountCredentials, context, roles);
+            try {
+                JsonObject serviceAccountCredentials = JsonParser.parseReader(reader).getAsJsonObject();
+                return getBearerTokenFromCredentials(serviceAccountCredentials, context, roles);
+            } finally {
+                try { reader.close(); } catch (IOException ignored) {}
+            }
         } catch (JsonSyntaxException e) {
             LogUtil.printErrorLog(ErrorLogs.INVALID_CREDENTIALS_FILE_FORMAT.getLog());
             throw new SkyflowException(ErrorCode.INVALID_INPUT.getCode(), Utils.parameterizedString(

src/main/java/com/skyflow/serviceaccount/util/SignedDataTokens.java

@@ -16,6 +16,7 @@
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.FileReader;
+import java.io.IOException;
 import java.security.PrivateKey;
 import java.util.ArrayList;
 import java.util.Date;
@@ -55,8 +56,12 @@ private static List<SignedDataTokenResponse> generateSignedTokenFromCredentialsF
                 throw new SkyflowException(ErrorCode.INVALID_INPUT.getCode(), ErrorMessage.InvalidCredentials.getMessage());
             }
             FileReader reader = new FileReader(String.valueOf(credentialsFile));
-            JsonObject serviceAccountCredentials = JsonParser.parseReader(reader).getAsJsonObject();
-            responseToken = generateSignedTokensFromCredentials(serviceAccountCredentials, dataTokens, timeToLive, context);
+            try {
+                JsonObject serviceAccountCredentials = JsonParser.parseReader(reader).getAsJsonObject();
+                responseToken = generateSignedTokensFromCredentials(serviceAccountCredentials, dataTokens, timeToLive, context);
+            } finally {
+                try { reader.close(); } catch (IOException ignored) {}
+            }
         } catch (JsonSyntaxException e) {
             LogUtil.printErrorLog(ErrorLogs.INVALID_CREDENTIALS_FILE_FORMAT.getLog());
             throw new SkyflowException(ErrorCode.INVALID_INPUT.getCode(), Utils.parameterizedString(

src/main/java/com/skyflow/utils/HttpUtility.java

@@ -121,7 +121,7 @@ public static String formatJsonToFormEncodedString(JsonObject requestBody) {
         for (Map.Entry<String, String> currentEntry : jsonMap.entrySet())
             formEncodeString.append(makeFormEncodeKeyValuePair(currentEntry.getKey(), currentEntry.getValue()));
 
-        return formEncodeString.substring(0, formEncodeString.length() - 1);
+        return formEncodeString.length() == 0 ? "" : formEncodeString.substring(0, formEncodeString.length() - 1);
     }
 
     public static String formatJsonToMultiPartFormDataString(JsonObject requestBody, String boundary) {

src/main/java/com/skyflow/vault/controller/VaultController.java

@@ -3,6 +3,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -371,7 +372,7 @@ public DeleteResponse delete(DeleteRequest deleteRequest) throws SkyflowExceptio
             throw new SkyflowException(e.statusCode(), e, e.headers(), bodyString);
         }
         LogUtil.printInfoLog(InfoLogs.DELETE_SUCCESS.getLog());
-        return new DeleteResponse(result.getRecordIdResponse().get());
+        return new DeleteResponse(result.getRecordIdResponse().orElse(Collections.emptyList()));
     }
 
     public QueryResponse query(QueryRequest queryRequest) throws SkyflowException {