Fix JavaDoc

Author: emmyzhou-db

databricks-sdk-java/src/main/java/com/databricks/sdk/core/oauth/EnvVarIDTokenSource.java

@@ -35,6 +35,8 @@ public EnvVarIDTokenSource(String envVarName, Environment env) {
    * @throws IllegalArgumentException if the environment variable name is null or empty, or the
    *     environment is null.
    * @throws DatabricksException if the environment variable is not set or is empty.
+   * @throws NullPointerException if the environment variable name is null.
+   * @throws ClassCastException if the environment variable name is not a String.
    */
   @Override
   public IDToken getIDToken(String audience) {

databricks-sdk-java/src/main/java/com/databricks/sdk/core/oauth/FileIDTokenSource.java

@@ -76,15 +76,18 @@ public IDToken getIDToken(String audience) {
       throw new DatabricksException("Invalid file path: " + filePath, e);
     }
 
+    boolean isFileExists;
     try {
-      if (!Files.exists(path)) {
-        throw new DatabricksException(String.format(ERROR_FILE_NOT_FOUND, filePath));
-      }
+      isFileExists = Files.exists(path);
     } catch (SecurityException e) {
       throw new DatabricksException(
           String.format(ERROR_SECURITY_CHECK, filePath, e.getMessage()), e);
     }
 
+    if (!isFileExists) {
+      throw new DatabricksException(String.format(ERROR_FILE_NOT_FOUND, filePath));
+    }
+
     List<String> rawLines;
     try {
       rawLines = Files.readAllLines(path, StandardCharsets.UTF_8);