When Gradle tries to resolve a dependency with version containing "+", it does not consider the the "latest" version as specified by maven-matadata.xml. Instead, Gradle uses the "versions" lists and uses the built-in version selection algorithm to choose the latest version.

_Example_
Repository set to [1]http://repo.spring.io/plugins-release...
Dependency is: compile group: 'org.springframework.data', name: 'spring-data-mongodb', version: '1.5.+'

At the time of posting repository maven-metadata.xml contained:

<?xml version="1.0" encoding="UTF-8"?>
<metadata>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-mongodb</artifactId>
<version>1.0.1.RELEASE</version>
<versioning>
<latest>1.5.0.RELEASE</latest>
<release>1.5.0.RELEASE</release>
<versions>
.....
</versioning>
</metadata>

Repository artifacts (latest ones) with last modififed date were:

1.5.0.M1/ 09-Apr-2014 08:04
1.5.0.RC1/ 21-May-2014 21:46
1.5.0.RELEASE/ 20-May-2014 16:38

_Expected Result__
Dependency resolved to "1.5.0.RELEASE"

_Actual Result_
Dependency resolves to "1.5.0.RC1"

When Gradle resolves dependencies it takes "1.5.0.RC1" over "1.5.0.RELEASE" which is defined in maven-metadata.xml.
The built-in algorithm in Gradle has special handling for the "RC" suffix, implicitly considering these releases as newer than other releases with arbitrary suffixes. Gradle doesn't have any special handling for the "RELEASE" suffix.

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[1] http://repo.spring.io/plugins-release/org/springframework/data/spring-data-mongodb/