public String getDefinitionFile() {
        return definitionFile;
    }
Gets the location/filename in which the symbol is defined.

<p>Code generators should write the generated code for a
symbol in a file with the same name that is returned from this
method.

<p>This method returns an empty string if no value was provided
for either the declaration file or the definition file.

@return The name of the file the symbol is defined.
smithy-codegen-core/src/main/java/software/amazon/smithy/codegen/core/Symbol.java