Package org.apache.maven.cling.invoker.mvnup.goals

Class DuplicateElementStrategy

java.lang.Object

org.apache.maven.cling.invoker.mvnup.goals.AbstractUpgradeStrategy

org.apache.maven.cling.invoker.mvnup.goals.DuplicateElementStrategy

All Implemented Interfaces:

UpgradeStrategy

@Named
@Singleton
@Priority(21)
public class DuplicateElementStrategy
extends AbstractUpgradeStrategy

Strategy for removing duplicate XML elements in POM files.

Maven 4's stricter POM parser rejects duplicate XML elements (such as <artifactId>, <properties>, <version>, etc.) that Maven 3 silently accepted using last-wins semantics. This strategy scans each POM element's children and removes duplicates, keeping only the last occurrence of each element name.

This strategy only targets "scalar" elements at well-known POM schema positions — elements that should appear at most once within their parent according to the Maven POM schema. Elements inside list containers (e.g., <dependency> inside <dependencies>, <plugin> inside <plugins>) are not affected by this strategy since duplicate dependencies and plugins are handled by DeduplicateDependenciesStrategy.

Plugin <configuration> elements are skipped entirely, because they contain free-form, plugin-specific XML whose schema is not known to this tool. Treating same-named children as duplicates in configuration sections (e.g., multiple <arg> entries inside <compilerArgs>) would silently remove valid list entries and break builds.

See Also:

• #12530

Constructor Summary

Constructors

Constructor	Description
DuplicateElementStrategy()

Method Summary

Modifier and Type	Method	Description
protected UpgradeResult	doApply(UpgradeContext context, Map<Path,eu.maveniverse.domtrip.Document> pomMap)	Subclasses implement the actual upgrade logic here.
String	getDescription()	Gets a description of what this strategy does.
boolean	isApplicable(UpgradeContext context)	Checks if this strategy is applicable given the current options.

Methods inherited from class org.apache.maven.cling.invoker.mvnup.goals.AbstractUpgradeStrategy

apply, buildEffectiveModel, cleanupTempDirectory, computeAllArtifactCoordinates, createTempProjectStructure, extractArtifactCoordinatesWithParentResolution, findCommonRoot, getOptions, getSession, logSummary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.maven.cling.invoker.mvnup.goals.UpgradeStrategy

isOptionEnabled

Constructor Details

DuplicateElementStrategy

public DuplicateElementStrategy()

Method Details

isApplicable

public boolean isApplicable(UpgradeContext context)

Description copied from interface: UpgradeStrategy

Checks if this strategy is applicable given the current options.

Parameters:

context - the upgrade context

Returns:

true if this strategy should be applied

getDescription

public String getDescription()

Description copied from interface: UpgradeStrategy

Gets a description of what this strategy does.

Returns:

a human-readable description of the strategy

doApply

protected UpgradeResult doApply(UpgradeContext context,
 Map<Path,eu.maveniverse.domtrip.Document> pomMap)

Description copied from class: AbstractUpgradeStrategy

Subclasses implement the actual upgrade logic here.

Specified by:

doApply in class AbstractUpgradeStrategy

Parameters:

context - the upgrade context

pomMap - map of all POM files in the project

Returns:

the result of the upgrade operation