default byte[] getClassBytes(final String className) throws IOException {
    final InputStream is = this.getInputStream(className + CLASS_SUFFIX);
    if (is == null)
      return null;

    try (is) {
      return is.readAllBytes();
    }
  }
Get the full bytes for a class's contents.

@param className the class name, with no trailing {@code /}
@return the bytes, or {@code null} if no class with that name is present
@throws IOException if an error is encountered while reading the class data
src/org/jetbrains/java/decompiler/main/extern/IContextSource.java