Mechanism to configure Che with configs from different sources (eclipse-che#2175)

* helper class for set and restore system properties

* override configuration properties from system properties with "che." prefix of environment variables with "CHE_" prefix

* fix bug report warnings, typo and avoid unneeded compilations of Pattern

* Removed ApiEndpointProvider to avoid duplication with environment binding

Author: Andrii Parfonov

assembly/assembly-wsagent-war/src/main/java/org/eclipse/che/wsagent/server/WsAgentModule.java

@@ -16,7 +16,6 @@
 import com.google.inject.name.Names;
 
 import org.eclipse.che.ApiEndpointAccessibilityChecker;
-import org.eclipse.che.ApiEndpointProvider;
 import org.eclipse.che.EventBusURLProvider;
 import org.eclipse.che.UriApiEndpointProvider;
 import org.eclipse.che.UserTokenProvider;
@@ -39,9 +38,9 @@
 import org.eclipse.che.api.core.util.FileCleaner.FileCleanerModule;
 import org.eclipse.che.api.core.websocket.WebSocketMessageReceiver;
 import org.eclipse.che.api.core.websocket.WebSocketMessageTransmitter;
+import org.eclipse.che.api.core.websocket.impl.BasicWebSocketMessageTransmitter;
 import org.eclipse.che.api.core.websocket.impl.BasicWebSocketTransmissionValidator;
 import org.eclipse.che.api.core.websocket.impl.GuiceInjectorEndpointConfigurator;
-import org.eclipse.che.api.core.websocket.impl.BasicWebSocketMessageTransmitter;
 import org.eclipse.che.api.core.websocket.impl.WebSocketTransmissionValidator;
 import org.eclipse.che.api.git.GitConnectionFactory;
 import org.eclipse.che.api.git.GitUserResolver;
@@ -86,7 +85,6 @@ protected void configure() {
         bind(GitUserResolver.class).to(LocalGitUserResolver.class);
         bind(GitConnectionFactory.class).to(JGitConnectionFactory.class);
 
-        bind(String.class).annotatedWith(Names.named("api.endpoint")).toProvider(ApiEndpointProvider.class);
         bind(URI.class).annotatedWith(Names.named("api.endpoint")).toProvider(UriApiEndpointProvider.class);
         bind(String.class).annotatedWith(Names.named("user.token")).toProvider(UserTokenProvider.class);
         bind(WSocketEventBusClient.class).asEagerSingleton();

core/commons/che-core-commons-inject/pom.xml

@@ -75,6 +75,22 @@
             <scope>test</scope>
         </dependency>
         <dependency>
+            <groupId>org.eclipse.che.core</groupId>
+            <artifactId>che-core-commons-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-all</artifactId>
+            <version>${org.mockito.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>${org.mockito.version}</version>
+            <scope>test</scope>
+        </dependency>       <dependency>
             <groupId>org.testng</groupId>
             <artifactId>testng</artifactId>
             <scope>test</scope>
@@ -88,6 +104,7 @@
                 <configuration>
                     <environmentVariables>
                         <CHE_LOCAL_CONF_DIR>${project.build.directory}/conf</CHE_LOCAL_CONF_DIR>
+                        <CHE_SOME_OTHER_NAME>che_underscore_environment_variable_value</CHE_SOME_OTHER_NAME>
                     </environmentVariables>
                 </configuration>
             </plugin>

core/commons/che-core-commons-inject/src/main/java/org/eclipse/che/inject/CheBootstrap.java

@@ -11,7 +11,7 @@
 package org.eclipse.che.inject;
 
 /**
- * Exception happen during guice configuration faze.
+ * Exception happen during guice configuration phase.
  *
  * @author Sergii Kabashniuk
  */

core/commons/che-core-commons-inject/src/main/java/org/eclipse/che/inject/ConfigurationException.java

@@ -10,6 +10,7 @@
  *******************************************************************************/
 package org.eclipse.che.inject;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.inject.Module;
 
 import org.slf4j.Logger;
@@ -28,7 +29,8 @@
 public class ModuleScanner implements ServletContainerInitializer {
     private static final Logger LOG = LoggerFactory.getLogger(ModuleScanner.class);
 
-    private static final List<Module> modules = new ArrayList<>();
+    @VisibleForTesting
+    static final List<Module> modules = new ArrayList<>();
 
     public static List<Module> findModules() {
         return new ArrayList<>(modules);

core/commons/che-core-commons-inject/src/main/java/org/eclipse/che/inject/ModuleScanner.java

@@ -21,9 +21,11 @@
 
 /** @author andrew00x */
 public class StringArrayConverter extends AbstractModule implements TypeConverter {
+    private static final Pattern PATTERN = Pattern.compile(" *, *");
+
     @Override
     public Object convert(String value, TypeLiteral<?> toType) {
-        return Iterables.toArray(Splitter.on(Pattern.compile(" *, *")).split(value), String.class);
+        return Iterables.toArray(Splitter.on(PATTERN).split(value), String.class);
     }
 
     @Override