Attempts to read artifacts failed

Question

I am creating an eclipse plugin and building it with Maven 3.5.0. During the execution of the mvn -T 8 clean install I get some warnings:

[WARNING] Some attempts to read artifact osgi.bundle,org.eclipse.jdt.debug,3.9.1
.v20160128-1343 failed:

[WARNING]    An error occurred while transferring artifact canonical: 
osgi.bundle,org.eclipse.jdt.debug,3.9.1.v20160128-1343 from repository 
file:/d:/PluginRoot/source/plugs/xsd_sdk:

[WARNING]       Problems downloading artifact: 
osgi.bundle,org.eclipse.jdt.debug,3.9.1.v20160128-1343.:

[WARNING]          File has invalidcontent:C:\Users\Admin\AppData\Local\Temp
\signatureFile2830880020429242663.jar:

[WARNING]             Invalid content:plugin.xml
[WARNING]             Invalid content:about.html
[WARNING]             Invalid content:plugin.properties
[WARNING]             Invalid content:.api_description
[WARNING]             Invalid content:.options`

In the pom.xml from where I am running the clean install I have this tycho configuration:

<build>
    <plugins>
        <plugin>
            <groupId>org.eclipse.tycho</groupId>
            <artifactId>tycho-maven-plugin</artifactId>
            <version>${tycho-version}</version>
            <extensions>true</extensions>
        </plugin>

        <plugin>
            <groupId>org.eclipse.tycho</groupId>
            <artifactId>target-platform-configuration</artifactId>
            <version>${tycho-version}</version>
            <configuration>
                <resolver>p2</resolver>
                <environments>
                    <environment>
                        <os>win32</os>
                        <ws>win32</ws>
                        <arch>x86_64</arch>
                    </environment>
                </environments>
                <includePackedArtifacts>true</includePackedArtifacts>
            </configuration>
        </plugin>

        <plugin>
            <groupId>org.eclipse.tycho</groupId>
            <artifactId>tycho-surefire-plugin</artifactId>
            <version>${tycho-version}</version>
        </plugin>

I don't know if this may be a problem, I am running behind a company proxy, but I already set the proxy setting in the settings.xml file of the maven version used.

Why do I get such warnings and how could I fix them?