presto-main/src/main/java/io/prestosql/sql/gen/PageFunctionCompiler.java/PageFunctionCompiler/compileProjection
class PageFunctionCompiler:    public Supplier<PageProjection> compileProjection(RowExpression projection, Optional<String> classNameSuffix)
    {
        if (projectionCache == null) {
            return compileProjectionInternal(projection, classNameSuffix);
        }
        return projectionCache.getUnchecked(projection);
    }