Fix Eclipse warnings in com.facebook.buck.maven package.

Summary:
Normally, these would be caught by Ant, but `com.facebook.buck.maven`
is excluded from Ant compilation for the time being.

Test Plan: Yellow warning icons disappear in Eclipse.

src/com/facebook/buck/maven/Resolver.java

@@ -392,10 +392,12 @@ public Prebuilt(String name, Path binaryJar) {
       this.binaryJar = binaryJar;
     }
 
+    @SuppressWarnings("unused") // This method is read reflectively.
     public String getName() {
       return name;
     }
 
+    @SuppressWarnings("unused") // This method is read reflectively.
     public Path getBinaryJar() {
       return binaryJar;
     }
@@ -404,6 +406,7 @@ public void setSourceJar(Path sourceJar) {
       this.sourceJar = sourceJar;
     }
 
+    @SuppressWarnings("unused") // This method is read reflectively.
     public Path getSourceJar() {
       return sourceJar;
     }
@@ -412,6 +415,7 @@ public void addDep(String dep) {
       this.deps.add(dep);
     }
 
+    @SuppressWarnings("unused") // This method is read reflectively.
     public SortedSet<String> getDeps() {
       return deps;
     }
@@ -420,6 +424,7 @@ public void addVisibility(String dep) {
       this.visibilities.add(dep);
     }
 
+    @SuppressWarnings("unused") // This method is read reflectively.
     public SortedSet<String> getVisibility() {
       return visibilities;
     }

test/com/facebook/buck/maven/ResolverIntegrationTest.java

@@ -249,6 +249,6 @@ public void shouldOmitTargetsInTheSameBuildFileInVisibilityArguments() throws Ex
 
     // Although the "deps-in-same-project" could be in the visibility param, it doesn't need to be
     // because it's declared in the same build file.
-    assertEquals(0, ((Collection) noDeps.get("visibility")).size());
+    assertEquals(0, ((Collection<?>) noDeps.get("visibility")).size());
   }
 }