logs from issue #138 indicate multiple modules are calling a non-threadsafe operation; as such, the mojo is being marked as threadSafe=false

dependency-check-maven/src/main/java/org/owasp/dependencycheck/maven/AggregateMojo.java

@@ -48,7 +48,7 @@ import org.owasp.dependencycheck.utils.Settings;
         name = "aggregate",
         defaultPhase = LifecyclePhase.VERIFY,
         /*aggregator = true,*/
-        threadSafe = true,
+        threadSafe = false,
         requiresDependencyResolution = ResolutionScope.COMPILE_PLUS_RUNTIME,
         requiresOnline = true
 )

dependency-check-maven/src/main/java/org/owasp/dependencycheck/maven/CheckMojo.java

@@ -36,7 +36,7 @@ import org.owasp.dependencycheck.utils.Settings;
 @Mojo(
         name = "check",
         defaultPhase = LifecyclePhase.VERIFY,
-        threadSafe = true,
+        threadSafe = false,
         requiresDependencyResolution = ResolutionScope.COMPILE_PLUS_RUNTIME,
         requiresOnline = true
 )

dependency-check-maven/src/main/java/org/owasp/dependencycheck/maven/PurgeMojo.java

@@ -35,7 +35,7 @@ import org.owasp.dependencycheck.utils.Settings;
 @Mojo(
         name = "purge",
         defaultPhase = LifecyclePhase.GENERATE_RESOURCES,
-        threadSafe = true,
+        threadSafe = false,
         requiresDependencyResolution = ResolutionScope.NONE,
         requiresOnline = true
 )

dependency-check-maven/src/main/java/org/owasp/dependencycheck/maven/UpdateMojo.java

@@ -34,7 +34,7 @@ import org.owasp.dependencycheck.utils.Settings;
 @Mojo(
         name = "update-only",
         defaultPhase = LifecyclePhase.GENERATE_RESOURCES,
-        threadSafe = true,
+        threadSafe = false,
         requiresDependencyResolution = ResolutionScope.NONE,
         requiresOnline = true
 )