diff --git a/etc/api/shared.yaml b/etc/api/shared.yaml
index d88f9eff61..6fc6e4dda5 100644
--- a/etc/api/shared.yaml
+++ b/etc/api/shared.yaml
@@ -27,7 +27,6 @@ api:
     # Has a struct field called 'async', which is now reserved
     - homegraph
     - gkehub
-    - spanner
     - firebaserules
     - servicemanagement
     # defines its own `Option` type
diff --git a/src/generator/lib/types.py b/src/generator/lib/types.py
index a816886b6d..f3187b689b 100644
--- a/src/generator/lib/types.py
+++ b/src/generator/lib/types.py
@@ -70,7 +70,7 @@ RUST_TYPE_RND_MAP = {
     f"{CHRONO_PATH}::Duration": lambda: f"chrono::Duration::seconds({randint(0, 9999999)})",
     CHRONO_DATE: chrono_date,
     CHRONO_DATETIME: lambda: CHRONO_UTC_NOW,
-    "FieldMask": lambda: f"FieldMask(vec![{choice(WORDS)}])",
+    "FieldMask": lambda: "FieldMask::new::<&str>(&[])",
 }
 
 JSON_TO_RUST_DEFAULT = {
diff --git a/src/generator/lib/util.py b/src/generator/lib/util.py
index b6a9831104..e5ae557cdb 100644
--- a/src/generator/lib/util.py
+++ b/src/generator/lib/util.py
@@ -1059,7 +1059,9 @@ def mb_additional_type_params(m):
 
 # return type name for a method on the given resource
 def mb_type(r, m):
-    return "%s%sCall" % (singular(canonical_type_name(r)), dot_sep_to_canonical_type_name(m))
+    resource = singular(canonical_type_name(r))
+    method = dot_sep_to_canonical_type_name(m)
+    return unique(f"{r}: {m}", f"{resource}{method}Call")
 
 
 # canonicalName = util.canonical_name()
@@ -1158,10 +1160,12 @@ def method_name_to_variant(name):
 # given a rust type-name (no optional, as from to_rust_type), you will get a suitable random default value
 # as string suitable to be passed as reference (or copy, where applicable)
 def rnd_arg_val_for_type(tn):
-    try:
-        return str(RUST_TYPE_RND_MAP[tn]())
-    except KeyError:
-        return '&Default::default()'
+    segments = tn.split("::")
+    for index in range(len(segments)):
+        name = "::".join(segments[index:])
+        if name in RUST_TYPE_RND_MAP:
+            return str(RUST_TYPE_RND_MAP[name]())
+    return "&Default::default()"
 
 
 # Converts a size to the respective integer
@@ -1190,5 +1194,21 @@ def string_impl(p):
         "string": lambda x: x
     }.get(p.get("format", p["type"]), lambda x: f"{x}.to_string()")
 
+
+def unique(
+    original: str,
+    desired: str,
+    attempts: int = 0,
+    assigned: dict[str, str] = {},
+) -> str:
+    if original in assigned:
+        return assigned[original]
+    candidate = desired + ("" if attempts == 0 else str(attempts))
+    if candidate not in assigned.values():
+        assigned[original] = candidate
+        return candidate
+    return unique(original, desired, attempts + 1)
+
+
 if __name__ == '__main__':
     raise AssertionError('For import only')