Maven Dependencies can't be resolved

I'm using Apache Maven3 and since two or three days some dependencies can't be resolved any more, which first have not had a problem. To be more specific its:

1. maven-findbgs-plugin:plugin:1.3.1
2. maven-cobertura-plugin:plugin:1.3

Shouldn't they be included by maven itself?

My pom.xml file:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <artifactId>xyz</artifactId>
  <name>xyz</name>
  <description>xyz</description>
  <repositories>
      <repository>  
        <id>prime-repo</id>  
        <name>PrimeFaces Maven Repository</name>  
        <url>http://repository.primefaces.org</url>  
        <layout>default</layout>  
    </repository>  
  </repositories>
  <dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${springframework-version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.webflow</groupId>
        <artifactId>spring-faces</artifactId>
        <version>${springwebflow-version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-core</artifactId>
        <version>${springsecurity-version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-config</artifactId>