[SET-679] Add FIRST merge strategy

pom.xml

@@ -392,6 +392,8 @@
                 <configuration>
                     <source>11</source>
                     <target>11</target>
+                    <testSource>11</testSource>
+                    <testTarget>11</testTarget>
                 </configuration>
             </plugin>
             <plugin>

src/main/java/org/wildfly/prospero/extras/manifest/merge/ManifestMergeCommand.java

@@ -3,7 +3,6 @@
 import org.wildfly.channel.ChannelManifest;
 import org.wildfly.channel.ChannelManifestMapper;
 import org.wildfly.channel.Stream;
-import org.wildfly.channel.version.VersionMatcher;
 import picocli.CommandLine;
 
 import java.nio.file.Path;
@@ -14,14 +13,20 @@
 import java.util.concurrent.Callable;
 import java.util.stream.Collectors;
 
-@CommandLine.Command(name = "merge")
+@CommandLine.Command(name = "manifest-merge")
 public class ManifestMergeCommand implements Callable<Integer> {
     @CommandLine.Parameters(index = "0")
     Path manifestOne;
 
     @CommandLine.Parameters(index = "1")
     Path manifestTwo;
 
+    @CommandLine.Option(names = {"--mode"}, defaultValue = "LATEST")
+    VersionMergeStrategy.Strategies mergeStrategy;
+
+    @CommandLine.Option(names = {"-h", "--help"}, usageHelp = true)
+    boolean help;
+
     @Override
     public Integer call() throws Exception {
 
@@ -39,7 +44,8 @@ public Integer call() throws Exception {
             if (!presentKeys.containsKey(key)) {
                 merged.add(s);
             } else {
-                if (VersionMatcher.COMPARATOR.compare(s.getVersion(), presentKeys.get(key).getVersion()) > 0) {
+                final String version = mergeStrategy.merge(presentKeys.get(key).getVersion(), s.getVersion());
+                if (!version.equals(presentKeys.get(key).getVersion())) {
                     merged.remove(presentKeys.get(key));
                     merged.add(s);
                 }

src/main/java/org/wildfly/prospero/extras/manifest/merge/VersionMergeStrategy.java

@@ -0,0 +1,41 @@
+package org.wildfly.prospero.extras.manifest.merge;
+
+import org.wildfly.channel.version.VersionMatcher;
+
+interface VersionMergeStrategy {
+    enum Strategies implements VersionMergeStrategy {
+        LATEST(new LatestMergeStrategy()),
+        FIRST(new FirstMergeStrategy());
+
+        private final VersionMergeStrategy mergeStrategy;
+
+        Strategies(VersionMergeStrategy mergeStrategy) {
+            this.mergeStrategy = mergeStrategy;
+        }
+
+        public String merge(String v1, String v2) {
+            return mergeStrategy.merge(v1, v2);
+        }
+    }
+    String merge(String v1, String v2);
+}
+
+class FirstMergeStrategy implements VersionMergeStrategy {
+
+    @Override
+    public String merge(String v1, String v2) {
+        return v1;
+    }
+}
+
+class LatestMergeStrategy implements VersionMergeStrategy {
+
+    @Override
+    public String merge(String v1, String v2) {
+        if (VersionMatcher.COMPARATOR.compare(v2, v1) > 0) {
+            return v2;
+        } else {
+            return v1;
+        }
+    }
+}

src/main/resources/UsageMessages.properties

@@ -6,4 +6,14 @@ feature-packs=Comma-separated list of Galleon feature packs to resolve the artif
 fp-mapper=Method to be used to resolve the artifacts from Galleon feature packs. Available values are ZIP and OFFLINER
 include-sources=If the source jars are available, download and include them in the generated repository.
 include-poms=Download and include artifacts' poms in the generated repository.
-out=Path to the generated repository
+out=Path to the generated repository
+
+tools.manifest-merge.usage.header=Merges streams from two manifests.
+tools.manifest-merge.usage.description.0=Prints a manifest containing streams from both input manifests. If the same\
+  stream is available in both input manifests, the conflict is resolved using a merge strategy.
+tools.manifest-merge.usage.description.1=The LATEST merge strategy compares the versions and picks the latest stream.
+tools.manifest-merge.usage.description.2=The FIRST merge strategy chooses the stream from `<manifestOne>`.
+mode=merge strategy to use. The default strategy is ${DEFAULT-VALUE}.
+
+usage.parameterListHeading = %nPositional parameters:%n
+usage.optionListHeading = %nOptions:%n

src/test/java/org/wildfly/prospero/extras/manifest/merge/VersionMergeStrategyTest.java

@@ -0,0 +1,22 @@
+package org.wildfly.prospero.extras.manifest.merge;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class VersionMergeStrategyTest {
+
+    @Test
+    public void testLatestVersionMerge() {
+        final VersionMergeStrategy latest = new LatestMergeStrategy();
+        assertEquals("1.2.4", latest.merge("1.2.3", "1.2.4"));
+        assertEquals("1.2.4", latest.merge("1.2.4", "1.2.3"));
+    }
+
+    @Test
+    public void testFirstVersionMerge() {
+        final VersionMergeStrategy first = new FirstMergeStrategy();
+        assertEquals("1.2.3", first.merge("1.2.3", "1.2.4"));
+        assertEquals("1.2.4", first.merge("1.2.4", "1.2.3"));
+    }
+}