eclipse 中离线安装activiti插件，报错“An error occurred while collecting items to be installed session context was:(...”
按照文章：eclipse离线安装Activiti Designer插件，下载插件的两个离线安装文件，并按照步骤安装后，一直next后报错，如下：
An error occurred while collecting items to be installed
session context was:(profile=SDKProfile, phase=org.eclipse.equinox.internal.p2.engine.phases.Collect, operand=, action=).
No repository found containing: osgi.bundle,org.apache.commons.io,2.2.0.v201405211200
No repository found containing: osgi.bundle,org.apache.commons.lang,2.6.0.v201404270220
No repository found containing: osgi.bundle,org.apache.xerces,2.9.0.v201101211617
No repository found containing: osgi.bundle,org.apache.xml.resolver,1.2.0.v201005080400
No repository found containing: osgi.bundle,org.apache.xml.serializer,2.7.1.v201005080400
No repository found containing: osgi.bundle,org.eclipse.draw2d,3.10.0.201506010206
No repository found containing: osgi.bundle,org.eclipse.emf,2.6.0.v20150601-0402
No repository found containing: osgi.bundle,org.eclipse.emf.common.ui,2.10.0.v20150601-0402
No repository found containing: osgi.bundle,org.eclipse.emf.edit,2.11.0.v20150601-0402
No repository found containing: osgi.bundle,org.eclipse.emf.edit.ui,2.11.0.v20150601-0402
No repository found containing: osgi.bundle,org.eclipse.emf.transaction,1.9.0.201506010221
No repository found containing: osgi.bundle,org.eclipse.emf.validation,1.8.0.201505312255
No repository found containing: osgi.bundle,org.eclipse.gef,3.10.0.201506010206
No repository found containing: osgi.bundle,org.eclipse.wst.common.core,1.2.0.v200908251833
No repository found containing: osgi.bundle,org.eclipse.wst.common.environment,1.0.400.v200912181831
No repository found containing: osgi.bundle,org.eclipse.wst.common.frameworks,1.2.200.v201304241450
No repository found containing: osgi.bundle,org.eclipse.wst.common.frameworks.ui,1.2.400.v201504292002
No repository found containing: osgi.bundle,org.eclipse.wst.common.project.facet.core,1.4.300.v201111030423
No repository found containing: osgi.bundle,org.eclipse.wst.common.ui,1.1.500.v200911182011
No repository found containing: osgi.bundle,org.eclipse.wst.common.uriresolver,1.2.200.v201505132009
No repository found containing: osgi.bundle,org.eclipse.wst.sse.core,1.1.900.v201401092025
No repository found containing: osgi.bundle,org.eclipse.wst.sse.ui,1.3.400.v201505141512
No repository found containing: osgi.bundle,org.eclipse.wst.validation,1.2.600.v201501211647
No repository found containing: osgi.bundle,org.eclipse.wst.validation.ui,1.2.500.v201310231452
No repository found containing: osgi.bundle,org.eclipse.wst.xml.core,1.1.902.v201501211904
No repository found containing: osgi.bundle,org.eclipse.wst.xml.ui,1.1.501.v201501212057
后上网查找文章：
An error occurred while collecting items to be installed session context was:(profile=epp.package.je
原因在于：出现错误的原因是Eclipse的更新管理P2出错了。p2有它的一个垃圾回收机制，之前删除的JAR包在未被回收之前，再次重装，系统不会做重新download的动作，但是它又找不到那个JAR包了，故而报错。
解决办法：
在运行命令行中切换到Eclipse的安装根目录，即eclipse.exe所在目录执行命令:
eclipse -application org.eclipse.equinox.p2.garbagecollector.application -profile **** （****是configuration/concfig.ini里eclipse.p2.profile项的值）。
上面的命令有点看不懂，“**** ””这到底是是填这个**** ，还是按照后面括号的注释填入新的值，有点懵，主要是eclipse.p2.profile项的值我找了，但不明确到底
等于哪段值。反正试了，最后报错，但还是安装成功了。
我的安装过程记录如下：
1.进eclipse根目录：
2.执行上面的命令行：
其中，第1个直接启动了eclipse成功未报错，第2、3条启动eclipse后，报错，也就是为成功启动eclipse。
硬头皮试了一下，反正最后我在eclipse中再安装插件包时没有报错了，直接安装成功，不知道是这三个中的哪个起效果了。记录一下，以后再次安装时多试验几遍，看哪个起作用的。