These are the packages that would be merged, in reverse order:

Calculating dependencies  ... done!
[ebuild  N    ] dev-java/maven-core-2.2.1  USE="doc source" 0 kB [1]

Total: 1 package (1 new), Size of downloads: 0 kB
Portage tree and overlays:
 [0] /usr/portage
 [1] /usr/local/portage/gsoc-maven-overlay

>>> Verifying ebuild manifests


>>> Emerging (1 of 1) dev-java/maven-core-2.2.1 from gsoc-maven-overlay
 * maven-core-2.2.1.tar.bz2 RMD160 SHA1 SHA256 size ;-) ...              [ ok ]
 * Package:    dev-java/maven-core-2.2.1
 * Repository: gsoc-maven-overlay
 * Maintainer: java@gentoo.org
 * USE:        consolekit doc elibc_glibc kernel_linux policykit source test userland_GNU x86
 * FEATURES:   sandbox test
debug: inherit: java-utils-2 -> /usr/portage/eclass/java-utils-2.eclass
debug: *** Multiple Inheritence (Level: 2)
debug: inherit: eutils -> /usr/portage/eclass/eutils.eclass
debug: *** Multiple Inheritence (Level: 3)
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: *** Multiple Inheritence (Level: 4)
debug: inherit: toolchain-funcs -> /usr/portage/eclass/toolchain-funcs.eclass
debug: inherit: portability -> /usr/portage/eclass/portability.eclass
debug: inherit: versionator -> /usr/portage/eclass/versionator.eclass
debug: *** Multiple Inheritence (Level: 3)
debug: inherit: eutils -> /usr/portage/eclass/eutils.eclass
debug: *** Multiple Inheritence (Level: 4)
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: inherit: portability -> /usr/portage/eclass/portability.eclass
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug:   eclass exists: /home/kasun/gentoo-sources/java/gsoc-maven-overlay/eclass/java-maven-2.eclass
debug: inherit: java-maven-2 -> /home/kasun/gentoo-sources/java/gsoc-maven-overlay/eclass/java-maven-2.eclass
debug: *** Multiple Inheritence (Level: 2)
debug: inherit: base -> /usr/portage/eclass/base.eclass
debug: *** Multiple Inheritence (Level: 3)
debug: inherit: eutils -> /usr/portage/eclass/eutils.eclass
debug: *** Multiple Inheritence (Level: 4)
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: inherit: portability -> /usr/portage/eclass/portability.eclass
debug: EXPORT_FUNCTIONS: src_unpack -> base_src_unpack
debug: EXPORT_FUNCTIONS: src_compile -> base_src_compile
debug: EXPORT_FUNCTIONS: src_install -> base_src_install
debug: EXPORT_FUNCTIONS: src_prepare -> base_src_prepare
debug: EXPORT_FUNCTIONS: src_configure -> base_src_configure
debug: inherit: java-pkg-2 -> /usr/portage/eclass/java-pkg-2.eclass
debug: *** Multiple Inheritence (Level: 3)
debug: inherit: java-utils-2 -> /usr/portage/eclass/java-utils-2.eclass
debug: *** Multiple Inheritence (Level: 4)
debug: inherit: eutils -> /usr/portage/eclass/eutils.eclass
debug: *** Multiple Inheritence (Level: 5)
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: inherit: portability -> /usr/portage/eclass/portability.eclass
debug: inherit: versionator -> /usr/portage/eclass/versionator.eclass
debug: *** Multiple Inheritence (Level: 5)
debug: inherit: eutils -> /usr/portage/eclass/eutils.eclass
debug: *** Multiple Inheritence (Level: 6)
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: inherit: portability -> /usr/portage/eclass/portability.eclass
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: EXPORT_FUNCTIONS: pkg_setup -> java-pkg-2_pkg_setup
debug: EXPORT_FUNCTIONS: src_prepare -> java-pkg-2_src_prepare
debug: EXPORT_FUNCTIONS: src_compile -> java-pkg-2_src_compile
debug: EXPORT_FUNCTIONS: pkg_preinst -> java-pkg-2_pkg_preinst
debug: inherit: java-ant-2 -> /usr/portage/eclass/java-ant-2.eclass
debug: *** Multiple Inheritence (Level: 3)
debug: inherit: java-utils-2 -> /usr/portage/eclass/java-utils-2.eclass
debug: *** Multiple Inheritence (Level: 4)
debug: inherit: eutils -> /usr/portage/eclass/eutils.eclass
debug: *** Multiple Inheritence (Level: 5)
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: inherit: portability -> /usr/portage/eclass/portability.eclass
debug: inherit: versionator -> /usr/portage/eclass/versionator.eclass
debug: *** Multiple Inheritence (Level: 5)
debug: inherit: eutils -> /usr/portage/eclass/eutils.eclass
debug: *** Multiple Inheritence (Level: 6)
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: inherit: portability -> /usr/portage/eclass/portability.eclass
debug: inherit: multilib -> /usr/portage/eclass/multilib.eclass
debug: java-pkg_ant-tasks-depend: entering function, parameters:
debug: EXPORT_FUNCTIONS: src_configure -> java-ant-2_src_configure
debug: EXPORT_FUNCTIONS: src_unpack -> java-maven-2_src_unpack
debug: EXPORT_FUNCTIONS: src_compile -> java-maven-2_src_compile
debug: EXPORT_FUNCTIONS: src_install -> java-maven-2_src_install
debug: java-pkg_init: entering function, parameters:
debug: java-pkg_init_paths_: entering function, parameters:
debug: JAVA_PKG_SHAREPATH: /usr/share/maven-core
debug: JAVA_PKG_ENV: /var/tmp/portage/dev-java/maven-core-2.2.1/image//usr/share/maven-core/package.env
debug: JAVA_PKG_JARDEST: /usr/share/maven-core/lib
debug: JAVA_PKG_LIBDEST: /usr/lib/maven-core
debug: JAVA_PKG_WARDEST: /usr/share/maven-core/webapps
debug: java-pkg_switch-vm: entering function, parameters:
debug: java-pkg_needs-vm: entering function, parameters:
debug: depend-java-query:  NV_DEPEND:	>=virtual/jdk-1.5
dev-java/maven-settings:0
dev-java/maven-plugin-parameter-documenter:0
dev-java/wagon-http-lightweight:0
dev-java/wagon-http:0
dev-java/maven-profile:0
dev-java/maven-model:0
dev-java/maven-artifact:0
dev-java/wagon-provider-api:0
dev-java/plexus-container-default:1.0_alpha33
dev-java/maven-repository-metadata:0
dev-java/maven-error-diagnostics:0
dev-java/maven-project:0
dev-java/commons-cli:1
dev-java/maven-plugin-api:0
dev-java/maven-plugin-descriptor:0
dev-java/plexus-interactivity-api:0
dev-java/maven-artifact-manager:0
dev-java/maven-monitor:0
dev-java/wagon-ssh
dev-java/plexus-utils:1.5
dev-java/classworlds:1.1
dev-java/plexus-sec-dispatcher
dev-java/plexus-interpolation:0
dev-java/wagon-http-shared:0
dev-java/nekohtml
dev-java/jsch:0
dev-java/plexus-cipher:0
dev-java/backport-util-concurrent:0

	dev-java/plexus-container-default:1.0_alpha33  >=dev-java/java-config-2.1.9-r1  source? ( app-arch/zip )  >=dev-java/ant-core-1.7.0


       >=dev-java/javatoolkit-0.3.0-r2
       >=dev-lang/python-2.4 >=dev-java/javatoolkit-0.3.0-r2
debug: Using: sun-jdk-1.6
debug: java-pkg_setup-vm: entering function, parameters:
debug: java-pkg_get-vm-vendor: entering function, parameters:
debug: java-pkg_is-vm-version-ge: entering function, parameters: 1.5
debug: java-pkg_get-vm-version: entering function, parameters:
debug: Detected a JDK(1.6) >= 1.5
debug: java-pkg_javac-args: entering function, parameters:
debug: want source: 1.5
debug: want target: 1.5
debug: java-pkg_is-vm-version-ge: entering function, parameters: 1.4
debug: java-pkg_get-vm-version: entering function, parameters:
debug: Detected a JDK(1.6) >= 1.4
debug: java-pkg_append_: entering function, parameters: LD_LIBRARY_PATH /opt/sun-jdk-1.6.0.25/jre/lib/i386/:/opt/sun-jdk-1.6.0.25/jre/lib/i386/native_threads/:/opt/sun-jdk-1.6.0.25/jre/lib/i386/xawt/:/opt/sun-jdk-1.6.0.25/jre/lib/i386/server/
 * Using: sun-jdk-1.6
>>> Unpacking source...
 * before maven unpack
debug: base_src_unpack: entering function, parameters:
>>> Unpacking maven-core-2.2.1.tar.bz2 to /var/tmp/portage/dev-java/maven-core-2.2.1/work
debug: java-pkg_getjars: entering function, parameters: maven-settings
debug: maven-settings:/usr/share/maven-settings/lib/maven-settings.jar
debug: java-pkg_ensure-dep: entering function, parameters: maven-settings
debug: Matching against: maven-settings
debug: java-pkg_record-jar_: entering function, parameters: maven-settings
debug: java-pkg_getjars: entering function, parameters: maven-plugin-parameter-documenter
debug: maven-plugin-parameter-documenter:/usr/share/maven-plugin-parameter-documenter/lib/maven-plugin-parameter-documenter.jar
debug: java-pkg_ensure-dep: entering function, parameters: maven-plugin-parameter-documenter
debug: Matching against: maven-plugin-parameter-documenter
debug: java-pkg_record-jar_: entering function, parameters: maven-plugin-parameter-documenter
debug: java-pkg_getjars: entering function, parameters: wagon-http-lightweight
debug: wagon-http-lightweight:/usr/share/wagon-http-lightweight/lib/wagon-http-lightweight.jar
debug: java-pkg_ensure-dep: entering function, parameters: wagon-http-lightweight
debug: Matching against: wagon-http-lightweight
debug: java-pkg_record-jar_: entering function, parameters: wagon-http-lightweight
debug: java-pkg_getjars: entering function, parameters: wagon-http
debug: wagon-http:/usr/share/wagon-http/lib/wagon-http.jar
debug: java-pkg_ensure-dep: entering function, parameters: wagon-http
debug: Matching against: wagon-http
debug: java-pkg_record-jar_: entering function, parameters: wagon-http
debug: java-pkg_getjars: entering function, parameters: maven-profile
debug: maven-profile:/usr/share/maven-profile/lib/maven-profile.jar
debug: java-pkg_ensure-dep: entering function, parameters: maven-profile
debug: Matching against: maven-profile
debug: java-pkg_record-jar_: entering function, parameters: maven-profile
debug: java-pkg_getjars: entering function, parameters: maven-model
debug: maven-model:/usr/share/maven-model/lib/maven-model.jar
debug: java-pkg_ensure-dep: entering function, parameters: maven-model
debug: Matching against: maven-model
debug: java-pkg_record-jar_: entering function, parameters: maven-model
debug: java-pkg_getjars: entering function, parameters: maven-artifact
debug: maven-artifact:/usr/share/maven-artifact/lib/maven-artifact.jar
debug: java-pkg_ensure-dep: entering function, parameters: maven-artifact
debug: Matching against: maven-artifact
debug: java-pkg_record-jar_: entering function, parameters: maven-artifact
debug: java-pkg_getjars: entering function, parameters: wagon-provider-api
debug: wagon-provider-api:/usr/share/wagon-provider-api/lib/wagon-provider-api.jar
debug: java-pkg_ensure-dep: entering function, parameters: wagon-provider-api
debug: Matching against: wagon-provider-api
debug: java-pkg_record-jar_: entering function, parameters: wagon-provider-api
debug: java-pkg_getjars: entering function, parameters: plexus-container-default-1.0_alpha33
debug: plexus-container-default-1.0_alpha33:/usr/share/plexus-container-default-1.0_alpha33/lib/plexus-container-default.jar
debug: java-pkg_ensure-dep: entering function, parameters: plexus-container-default-1.0_alpha33
debug: Matching against: plexus-container-default-1.0_alpha33
 * The ebuild is attempting to use plexus-container-default-1.0_alpha33 that is not declared in DEPEND.
 * ERROR: dev-java/maven-core-2.2.1 failed (unpack phase):
 *   The ebuild is attempting to use plexus-container-default-1.0_alpha33 that is not declared in DEPEND.
 *
 * Call stack:
 *     ebuild.sh, line   56:  Called src_unpack
 *   environment, line 4804:  Called java-maven-2_src_unpack
 *   environment, line 2783:  Called java-maven-2_rewrite_poms '/var/tmp/portage/dev-java/maven-core-2.2.1/work/maven-core-2.2.1/pom.xml'
 *   environment, line 2590:  Called java-pkg_getjars 'plexus-container-default-1.0_alpha33'
 *   environment, line 3540:  Called java-pkg_ensure-dep '' 'plexus-container-default-1.0_alpha33'
 *   environment, line 3250:  Called die
 * The specific snippet of code:
 *               die "${dev_error}";
 *
 * If you need support, post the output of 'emerge --info =dev-java/maven-core-2.2.1',
 * the complete build log and the output of 'emerge -pqv =dev-java/maven-core-2.2.1'.
 * This ebuild used the following eclasses from overlays:
 *   /home/kasun/gentoo-sources/java/gsoc-maven-overlay/eclass/java-maven-2.eclass
 * This ebuild is from an overlay named 'gsoc-maven-overlay': '/home/kasun/gentoo-sources/java/gsoc-maven-overlay/'
!!! When you file a bug report, please include the following information:
GENTOO_VM=sun-jdk-1.6  CLASSPATH="" JAVA_HOME="/opt/sun-jdk-1.6.0.25"
JAVACFLAGS="-source 1.5 -target 1.5" COMPILER=""
and of course, the output of emerge --info
 * The complete build log is located at '/var/tmp/portage/dev-java/maven-core-2.2.1/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/dev-java/maven-core-2.2.1/temp/environment'.
 * S: '/var/tmp/portage/dev-java/maven-core-2.2.1/work/maven-core-2.2.1'

>>> Failed to emerge dev-java/maven-core-2.2.1, Log file:

>>>  '/var/tmp/portage/dev-java/maven-core-2.2.1/temp/build.log'
 * Messages for package dev-java/maven-core-2.2.1: