private void ensureFrameIsMutable() {
        if (!((bitField0_ & 0x00000001) != 0)) {
          frame_ =
              new java.util.ArrayList<com.google.devtools.cloudtrace.v2.StackTrace.StackFrame>(
                  frame_);
          bitField0_ |= 0x00000001;
        }
      }
<pre>
A collection of stack frames, which can be truncated.
</pre>

Protobuf type {@code google.devtools.cloudtrace.v2.StackTrace.StackFrames}
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/StackTrace.java