public String[] getLiteralNames() {
		return literalNames;
	}
Returns a {@link VocabularyImpl} instance from the specified set of token
names. This method acts as a compatibility layer for the single
{@code tokenNames} array generated by previous releases of ANTLR.

<p>The resulting vocabulary instance returns {@code null} for
{@link #getLiteralName(int)} and {@link #getSymbolicName(int)}, and the
value from {@code tokenNames} for the display names.</p>

@param tokenNames The token names, or {@code null} if no token names are
available.
@return A {@link Vocabulary} instance which uses {@code tokenNames} for
the display names of tokens.
runtime/Java/src/org/antlr/v4/runtime/VocabularyImpl.java