diff --git a/pom.xml b/pom.xml
index 5ca3c35..64491fb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -31,6 +31,11 @@
 	<properties>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<project.build.sourceVersion>1.8</project.build.sourceVersion>
+		
+		<!-- workaround for: [WARNING] 'reporting.plugins.plugin.version' for ... -->
+		<jacoco-maven-plugin.version>0.7.4.201502262128</jacoco-maven-plugin.version><!-- invalid format 1007: <version>0.7.5.201505241946</version> -->
+		<maven-javadoc-plugin.version>2.10.3</maven-javadoc-plugin.version>
+		<maven-project-info-reports-plugin>2.8</maven-project-info-reports-plugin>
 	</properties>
 	<dependencyManagement>
 		<dependencies>
@@ -133,14 +138,6 @@
 				<plugin>
 					<artifactId>maven-source-plugin</artifactId>
 					<version>2.2.1</version>
-					<executions>
-						<execution>
-							<id>attach-sources</id>
-							<goals>
-								<goal>jar</goal>
-							</goals>
-						</execution>
-					</executions>
 				</plugin>
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
@@ -154,51 +151,15 @@
 						</dependency>
 					</dependencies>
 				</plugin>
-				<plugin>
-					<groupId>org.apache.maven.plugins</groupId>
-					<artifactId>maven-project-info-reports-plugin</artifactId>
-					<version>2.8</version>
-				</plugin>
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-javadoc-plugin</artifactId>
-					<version>2.10.3</version>
-				</plugin>
-				<plugin>
-					<groupId>org.apache.maven.plugins</groupId>
-					<artifactId>maven-pmd-plugin</artifactId>
-					<version>3.4</version>
-				</plugin>
-				<plugin>
-					<groupId>org.codehaus.mojo</groupId>
-					<artifactId>findbugs-maven-plugin</artifactId>
-					<version>3.0.0</version>
-				</plugin>
-				<plugin>
-					<groupId>org.apache.maven.plugins</groupId>
-					<artifactId>maven-checkstyle-plugin</artifactId>
-					<version>2.15</version>
-				</plugin>
-				<plugin>
-					<groupId>org.codehaus.mojo</groupId>
-					<artifactId>taglist-maven-plugin</artifactId>
-					<version>2.4</version>
-				</plugin>
-				<plugin>
-					<groupId>org.apache.maven.plugins</groupId>
-					<artifactId>maven-surefire-plugin</artifactId>
-					<version>2.18.1</version>
-				</plugin>
-				<plugin>
-					<groupId>org.apache.maven.plugins</groupId>
-					<artifactId>maven-surefire-report-plugin</artifactId>
-					<version>2.18.1</version>
+					<version>${maven-javadoc-plugin.version}</version>
 				</plugin>
 				<plugin>
 					<groupId>org.jacoco</groupId>
 					<artifactId>jacoco-maven-plugin</artifactId>
-					<version>0.7.4.201502262128</version>
-					<!-- invalid format 1007: <version>0.7.5.201505241946</version> -->
+					<version>${jacoco-maven-plugin.version}</version>
 				</plugin>
 			</plugins>
 		</pluginManagement>
@@ -280,6 +241,14 @@
 				<plugins>
 					<plugin>
 						<artifactId>maven-source-plugin</artifactId>
+						<executions>
+							<execution>
+								<id>attach-sources</id>
+								<goals>
+									<goal>jar</goal>
+								</goals>
+							</execution>
+						</executions>
 					</plugin>
 				</plugins>
 			</build>
@@ -295,6 +264,7 @@
 					<plugin>
 						<groupId>org.apache.maven.plugins</groupId>
 						<artifactId>maven-project-info-reports-plugin</artifactId>
+						<version>${maven-project-info-reports-plugin}</version>
 						<dependencies><!-- fix for jdk8 -->
 							<dependency>
 								<groupId>org.apache.maven.shared</groupId>
@@ -343,6 +313,7 @@
 					<plugin>
 						<groupId>org.apache.maven.plugins</groupId>
 						<artifactId>maven-project-info-reports-plugin</artifactId>
+						<version>${maven-project-info-reports-plugin}</version>
 						<configuration>
 							<aggregate>true</aggregate>
 							<dependencyDetailsEnabled>false</dependencyDetailsEnabled>
@@ -375,6 +346,7 @@
 					<plugin>
 						<groupId>org.apache.maven.plugins</groupId>
 						<artifactId>maven-javadoc-plugin</artifactId>
+						<version>${maven-javadoc-plugin.version}</version>
 						<configuration>
 							<aggregate>true</aggregate>
 							<quiet>true</quiet>
@@ -394,6 +366,7 @@
 					<plugin>
 						<groupId>org.apache.maven.plugins</groupId>
 						<artifactId>maven-pmd-plugin</artifactId>
+						<version>3.4</version>
 						<configuration>
 							<aggregate>true</aggregate>
 							<linkXref>true</linkXref>
@@ -405,6 +378,7 @@
 					<plugin>
 						<groupId>org.codehaus.mojo</groupId>
 						<artifactId>findbugs-maven-plugin</artifactId>
+						<version>3.0.0</version>
 						<configuration>
 							<aggregate>true</aggregate>
 							<findbugsXmlOutput>true</findbugsXmlOutput>
@@ -415,6 +389,7 @@
 					<plugin>
 						<groupId>org.apache.maven.plugins</groupId>
 						<artifactId>maven-checkstyle-plugin</artifactId>
+						<version>2.15</version>
 						<configuration>
 							<aggregate>true</aggregate>
 							<enableRulesSummary>true</enableRulesSummary>
@@ -424,6 +399,7 @@
 					<plugin>
 						<groupId>org.codehaus.mojo</groupId>
 						<artifactId>taglist-maven-plugin</artifactId>
+						<version>2.4</version>
 						<configuration>
 							<aggregate>true</aggregate>
 							<tags>
@@ -453,6 +429,7 @@
 					<plugin>
 						<groupId>org.apache.maven.plugins</groupId>
 						<artifactId>maven-surefire-report-plugin</artifactId>
+						<version>2.18.1</version>
 						<configuration>
 							<aggregate>true</aggregate>
 						</configuration>
@@ -467,6 +444,7 @@
 					<plugin>
 						<groupId>org.jacoco</groupId>
 						<artifactId>jacoco-maven-plugin</artifactId>
+						<version>${jacoco-maven-plugin.version}</version>
 						<configuration>
 							<aggregate>true</aggregate>
 							<goal>report</goal>