public Builder mergeOriginalFunctionName(
          com.google.devtools.cloudtrace.v2.TruncatableString value) {
        if (originalFunctionNameBuilder_ == null) {
          if (((bitField0_ & 0x00000002) != 0)
              && originalFunctionName_ != null
              && originalFunctionName_
                  != com.google.devtools.cloudtrace.v2.TruncatableString.getDefaultInstance()) {
            getOriginalFunctionNameBuilder().mergeFrom(value);
          } else {
            originalFunctionName_ = value;
          }
        } else {
          originalFunctionNameBuilder_.mergeFrom(value);
        }
        if (originalFunctionName_ != null) {
          bitField0_ |= 0x00000002;
          onChanged();
        }
        return this;
      }
<pre>
An un-mangled function name, if `function_name` is mangled.
To get information about name mangling, run
[this search](https://www.google.com/search?q=cxx+name+mangling).
The name can be fully-qualified (up to 1024 bytes).
</pre>

<code>.google.devtools.cloudtrace.v2.TruncatableString original_function_name = 2;</code>
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/StackTrace.java