return new UpgradeResult(Collections.emptySet(), Collections.emptySet(), Collections.emptySet());
    }

    /**
     * Merges this result with another result, combining the sets of POMs.
     * This allows proper aggregation of results from multiple strategies without double-counting.
     */
    public UpgradeResult merge(UpgradeResult other) {
        Set<Path> mergedProcessed = new HashSet<>(this.processedPoms);

)

// AST Node Evaluation functions
//
// During evaluation, the query is known to be valid, as analysis is
// complete. The only errors possible are due to value type
// mismatches, etc.
//
// If an aggregation node is present as a descendant (when
// e.prop.isAggregation is true), we call evalNode on all child nodes,
// check for errors, but do not perform any combining of the results

    public ProjectBuildList(List<ProjectSegment> items) {
        this.items = Collections.unmodifiableList(items);
    }

    // TODO Optimize; or maybe just rewrite the whole way aggregating mojos are being run.
    /**
     * Returns aProjectBuildList that contains only items for the specified taskSegment
     * @param taskSegment the requested task segment

 * into TaskSegments. This class represents the execution context of one such task segment.
 * </p>
 * <p>
 * Wise voices have suggested that maybe aggregators shouldn't be bound to the ordinary
 * lifecycle at all, in which case we wouldn't be needing this class at all ( and
 * ProjectBuildList.getByTaskSegments). Or maybe they should be introduced in the calculation

- All [operators](https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-operators.html) are supported.
- All aggregation, conditional, type-conversion and string functions are supported.
- JSON path expressions such as `FROM S3Object[*].path` are not yet evaluated.
- Large numbers (outside of the signed 64-bit range) are not yet supported.

    <suppress checks="JavadocPackage"
              files=".*[/\\]platforms[/\\]jvm[/\\]plugins-test-report-aggregation[/\\]src[/\\]main[/\\]java[/\\]org[/\\]gradle[/\\]api[/\\]plugins[/\\][^/\\]+"/>

    <suppress checks="JavadocPackage"

     *
     * <p>This calculation is only a heuristic based on our conventions.
     * In detail, the algo relies on the following assumptions: <ul>
     * <li>The parent uses aggregation and refers to the child via the modules section</li>
     * <li>The module path to the child is considered to
     * point at the POM rather than its base directory if the path ends with ".xml" (ignoring case)</li>

                    .longOpt("non-recursive")
                    .desc(
                            "Do not recurse into sub-projects. When used together with -pl, do not recurse into sub-projects of selected aggregators")
                    .get());
            options.addOption(Option.builder(UPDATE_SNAPSHOTS)
                    .longOpt("update-snapshots")

 * a file named {@code pom.xml} and loaded into a {@link org.apache.maven.api.model.Model Model}
 * instances.</p>
 *
 * <p><dfn>Project aggregation</dfn> allows building several projects together. This is only
 * for projects that are built, hence available on the file system. One project,
 * called the <dfn>aggregator project</dfn> lists one or more <dfn>sub-projects</dfn>

	Extract   *ExtractFunc   `parser:"| @@"`
	Trim      *TrimFunc      `parser:"| @@"`
	DateAdd   *DateAddFunc   `parser:"| @@"`
	DateDiff  *DateDiffFunc  `parser:"| @@"`

	// Used during evaluation for aggregation funcs
	aggregate *aggVal
}

// SimpleArgFunc represents functions with simple expression
// arguments.
type SimpleArgFunc struct {