adjusted mean branch id

src/main/java/gov/usgs/earthquake/nshmp/gmm/UsgsPrviBackbone2025.java

@@ -443,10 +443,10 @@ public abstract class UsgsPrviBackbone2025 implements GroundMotionModel {
 
     LogicTree.Builder<GroundMotion> tree = LogicTree.builder("gmm-tree-prvi-" + name);
     for (Branch<GroundMotion> b : base) {
-      tree.addBranch(MODEL_BASE_ID + " : " + b.id(), b.value(), b.weight() * 0.5);
+      tree.addBranch(MODEL_BASE_ID + "-" + b.id(), b.value(), b.weight() * 0.5);
     }
     for (Branch<GroundMotion> b : adj) {
-      tree.addBranch(MODEL_ADJUST_ID + " : " + b.id(), b.value(), b.weight() * 0.5);
+      tree.addBranch(MODEL_ADJUST_ID + "-" + b.id(), b.value(), b.weight() * 0.5);
     }
     return tree.build();
   }