code: private static StackLine getStackLine(SrcTree srcTree,
              String classQualifiedName, String methodSimpleName, int line) {
          StackLine rootStackLine = getStackLine(
                  srcTree.getRootMethodTable(), classQualifiedName, methodSimpleName, line);
          if (rootStackLine != null) {
              return rootStackLine;
          }
          StackLine subStackLine = getStackLine(
                  srcTree.getSubMethodTable(), classQualifiedName, methodSimpleName, line);
          if (subStackLine != null) {
              return subStackLine;
          }
          return null;
      }
docs: null means method does not exists in srcTree