Henrik Rueping created MNG-8174:
-----------------------------------
Summary: DefaultModelBuilder throws a NPE on self-referencing
property
Key: MNG-8174
URL: https://issues.apache.org/jira/browse/MNG-8174
Project: Maven
Issue Type: Bug
Affects Versions: 3.9.8, 3.9.5
Reporter: Henrik Rueping
The method org.apache.maven.model.building.DefaultModelBuilder.build(...)
throws a Null-Pointer Exception when trying to resolve a pom with a
self-referencing property, e.g.
{code:xml}
<properties>
<prop>${prop}</prop>
</properties>
{code}
A (rather) minimal example can be found at
[https://github.com/HenrikRueping/pom-property-resolution-test]
The stacktrace is
{code:java}
java.lang.NullPointerException: Attribute value can not be null
at org.codehaus.plexus.util.xml.Xpp3Dom.setAttribute(Xpp3Dom.java:208)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:725)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:730)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:730)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:730)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:730)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:693)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:674)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:524)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:571)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator$ModelVisitor.visit(StringVisitorModelInterpolator.java:232)
at
org.apache.maven.model.interpolation.StringVisitorModelInterpolator.interpolateModel(StringVisitorModelInterpolator.java:101)
at
org.apache.maven.model.building.DefaultModelBuilder.interpolateModel(DefaultModelBuilder.java:770)
at
org.apache.maven.model.building.DefaultModelBuilder.build(DefaultModelBuilder.java:385)
at
org.apache.maven.model.building.DefaultModelBuilder.build(DefaultModelBuilder.java:247)
{code}
It seems like the cause is that Xpp3Dom.setAttribute does not accept null
values,
but the interpolate Method
in org.apache.maven.model.interpolation.StringVisitorModelInterpolator returns
null on a self-referencing property.
My Expectation would be that in such a case either a ModelBuildingException is
thrown, or it behaves like in the usual case of an undefined property, e.g. the
string "${prop}" is in the parsed model.
Maybe it is a good idea to add for each test case with an undefined property an
analogous test case with a self-referencing property.
In Eclipse this Exception is still thrown when editing a pom with a
self-referencing property.
I would say this is a minor issue, currently I can simply catch the
NullPointerException hoping that there are no other causes for a
NullPointerException.
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