The method is a native method defined in fontpath.c

Java_sun_font_FontConfigManager_getFontConfig {

...
 cacheDirs = (*FcConfigGetCacheDirs)(NULL);
    935 if (cacheDirs != NULL) {
    936 while ((cnt < max) && (cacheDir = (*FcStrListNext)(cacheDirs))) {
    937 jstr = (*env)->NewStringUTF(env, (const char*)cacheDir);
    938 JNU_CHECK_EXCEPTION(env);
    939
    940 (*env)->SetObjectArrayElement(env, cacheDirArray, cnt++, jstr);
    941 (*env)->DeleteLocalRef(env, jstr);
    942 }
    943 (*FcStrListDone)(cacheDirs);
    944 }

...
}

cacheDir is allocated by (*FcConfigGetCacheDirs)(NULL), but inside the while loop, if there is an exception occurred, macro JNU_CHECK_EXCEPTION(env) [1] ; will return without calling (*FcStrListDone)(cacheDirs);, therefore, cacheDir is leaked.

[1] #define JNU_CHECK_EXCEPTION(env) \
    do { \
        if ((env)->ExceptionCheck()) { \
            return; \
        } \
    } while (0) \