Thank You for helping. Installing tycho connector resolved errors in pom.xml .Now these 10 errors remain mainly because org.eclipse.recommenders.tests.CodeBuilder and
org.eclipse.recommenders.completion.rcp.it.MockedIntelligentCompletionProposalComputer
these two classes cannot be found. How to solve this?
Extract from Eclipse problem window:
Description    Resource    Path    Location    Type
MockedIntelligentCompletionProposalComputer cannot be resolved to a type    Stubs.java    /org.eclipse.recommenders.calls.rcp.tests/src/org/eclipse/recommenders/calls/rcp/it    line 154    Java Problem
MockedIntelligentCompletionProposalComputer cannot be resolved to a type    Stubs.java    /org.eclipse.recommenders.calls.rcp.tests/src/org/eclipse/recommenders/calls/rcp/it    line 174    Java Problem
The import org.eclipse.recommenders.tests.CodeBuilder cannot be resolved    Bug399800Test.java    /org.eclipse.recommenders.completion.rcp.tests/src/org/eclipse/recommenders/completion/rcp/it    line 3    Java Problem
The import org.eclipse.recommenders.completion.rcp.it.MockedIntelligentCompletionProposalComputer cannot be resolved    Stubs.java    /org.eclipse.recommenders.calls.rcp.tests/src/org/eclipse/recommenders/calls/rcp/it    line 25    Java Problem
The method classDeclaration(String, String) is undefined for the type Bug404751Test    Bug404751Test.java    /org.eclipse.recommenders.completion.rcp.tests/src/org/eclipse/recommenders/completion/rcp/it    line 96    Java Problem
The method classbody(String, String) is undefined for the type Bug399800Test    Bug399800Test.java    /org.eclipse.recommenders.completion.rcp.tests/src/org/eclipse/recommenders/completion/rcp/it    line 70    Java Problem
CodeBuilder cannot be resolved    ReceiverTypeOfStaticMethodCallsTest.java    /org.eclipse.recommenders.completion.rcp.tests/src/org/eclipse/recommenders/completion/rcp/it    line 57    Java Problem
The method classDeclaration(String, String) is undefined for the type Bug404751Test    Bug404751Test.java    /org.eclipse.recommenders.completion.rcp.tests/src/org/eclipse/recommenders/completion/rcp/it    line 84    Java Problem
The import org.eclipse.recommenders.tests.CodeBuilder cannot be resolved    ReceiverTypeOfStaticMethodCallsTest.java    /org.eclipse.recommenders.completion.rcp.tests/src/org/eclipse/recommenders/completion/rcp/it    line 18    Java Problem
The import org.eclipse.recommenders.tests.CodeBuilder cannot be resolved    Bug404751Test.java    /org.eclipse.recommenders.completion.rcp.tests/src/org/eclipse/recommenders/completion/rcp/it    line 3    Java Problem