Revert^2 "Cache Java codegen'd flags in static member variables."

This reverts commit efda207c09de55f133b22d397a78add7673fd560.

Reason for revert: this unrevert contains the fix for b/311187402

Test: cargo test
Change-Id: I210aebd30edd864a7c141ede336c12aebf4f1fcd
diff --git a/tools/aconfig/templates/FeatureFlagsImpl.java.template b/tools/aconfig/templates/FeatureFlagsImpl.java.template
index ff089df..ec8822c 100644
--- a/tools/aconfig/templates/FeatureFlagsImpl.java.template
+++ b/tools/aconfig/templates/FeatureFlagsImpl.java.template
@@ -8,10 +8,41 @@
 {{ endif }}
 /** @hide */
 public final class FeatureFlagsImpl implements FeatureFlags \{
-{{ if is_read_write- }}
-{{ for properties in properties_set }}
-    private Properties {properties};
+{{- if is_read_write }}
+{{- for namespace_with_flags in namespace_flags }}
+    private static boolean {namespace_with_flags.namespace}_is_cached = false;
+{{- endfor- }}
+
+{{ for flag in flag_elements }}
+{{- if flag.is_read_write }}
+    private static boolean {flag.method_name} = {flag.default_value};
+{{- endif- }}
 {{ endfor }}
+
+{{ for namespace_with_flags in namespace_flags }}
+    private void load_overrides_{namespace_with_flags.namespace}() \{
+        try \{
+            Properties properties = DeviceConfig.getProperties("{namespace_with_flags.namespace}");
+
+            {{- for flag in namespace_with_flags.flags }}
+            {{- if flag.is_read_write }}
+            {flag.method_name} =
+                properties.getBoolean("{flag.device_config_flag}", {flag.default_value});
+            {{- endif- }}
+            {{ endfor }}
+        } catch (NullPointerException e) \{
+            throw new RuntimeException(
+                "Cannot read value from namespace {namespace_with_flags.namespace} "
+                + "from DeviceConfig. It could be that the code using flag "
+                + "executed before SettingsProvider initialization. Please use "
+                + "fixed read-only flag by adding is_fixed_read_only: true in "
+                + "flag declaration.",
+                e
+            );
+        }
+        {namespace_with_flags.namespace}_is_cached = true;
+    }
+{{ endfor- }}
 {{ endif- }}
 
 {{ for flag in flag_elements }}
@@ -19,45 +50,15 @@
     @UnsupportedAppUsage
     public boolean {flag.method_name}() \{
     {{ -if flag.is_read_write }}
-        if ({flag.properties} == null) \{
-            {flag.properties} =
-                getProperties(
-                    "{flag.device_config_namespace}",
-                    "{flag.device_config_flag}"
-                );
+        if (!{flag.device_config_namespace}_is_cached) \{
+            load_overrides_{flag.device_config_namespace}();
         }
-        return {flag.properties}
-                .getBoolean(
-                    "{flag.device_config_flag}",
-                    {flag.default_value}
-                );
+        return {flag.method_name};
     {{ else }}
         return {flag.default_value};
     {{ endif- }}
     }
 {{ endfor }}
-
-{{ -if is_read_write }}
-    private Properties getProperties(
-            String namespace,
-            String flagName) \{
-        Properties properties = null;
-        try \{
-            properties = DeviceConfig.getProperties(namespace);
-        } catch (NullPointerException e) \{
-            throw new RuntimeException(
-                "Cannot read value of flag " + flagName + " from DeviceConfig. "
-                + "It could be that the code using flag executed "
-                + "before SettingsProvider initialization. "
-                + "Please use fixed read-only flag by adding "
-                + "is_fixed_read_only: true in flag declaration.",
-                e
-            );
-        }
-
-        return properties;
-    }
-{{ endif- }}
 }
 {{ else }}
 {#- Generate only stub if in test mode #}
@@ -70,6 +71,6 @@
         throw new UnsupportedOperationException(
             "Method is not implemented.");
     }
-{{ endfor }}
+{{ endfor- }}
 }
 {{ endif }}