presto-main/src/main/java/io/prestosql/metadata/FunctionRegistry.java/FunctionRegistry/getScalarFunctionImplementation
class FunctionRegistry:    public ScalarFunctionImplementation getScalarFunctionImplementation(ResolvedFunction resolvedFunction)
    {
        try {
            return specializedScalarCache.getUnchecked(getSpecializedFunctionKey(resolvedFunction));
        }
        catch (UncheckedExecutionException e) {
            throwIfInstanceOf(e.getCause(), PrestoException.class);
            throw e;
        }
    }